func (_ERC20Interface *ERC20InterfaceFilterer) WatchApproval(opts *bind.WatchOpts, sink chan<- *ERC20InterfaceApproval, tokenOwner []common.Address, spender []common.Address) (event.Subscription, error) {
	var tokenOwnerRule []interface{}
	for _, tokenOwnerItem := range tokenOwner {
		tokenOwnerRule = append(tokenOwnerRule, tokenOwnerItem)
	}
	var spenderRule []interface{}
	for _, spenderItem := range spender {
		spenderRule = append(spenderRule, spenderItem)
	}
	logs, sub, err := _ERC20Interface.contract.WatchLogs(opts, "Approval", tokenOwnerRule, spenderRule)
	if err != nil {
		return nil, err
	}
	return event.NewSubscription(func(quit <-chan struct{}) error {
		defer sub.Unsubscribe()
		for {
			select {
			case log := <-logs:
				event := new(ERC20InterfaceApproval)
				if err := _ERC20Interface.contract.UnpackLog(event, "Approval", log); err != nil {
					return err
				}
				event.Raw = log
				select {
				case sink <- event:
				case err := <-sub.Err():
					return err
				case <-quit:
					return nil
				}
			case err := <-sub.Err():
				return err
			case <-quit:
				return nil
			}
		}
	}), nil
}
WatchApproval is a free log subscription operation binding the contract event 0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925.

Solidity: event Approval(address indexed tokenOwner, address indexed spender, uint256 tokens)
package eth
import (
	"math/big"
	"strings"
	ethereum "github.com/ethereum/go-ethereum"
	"github.com/ethereum/go-ethereum/accounts/abi"
	"github.com/ethereum/go-ethereum/accounts/abi/bind"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/event"
)
var (
	_ = big.NewInt
	_ = strings.NewReader
	_ = ethereum.NotFound
	_ = bind.Bind
	_ = common.Big1
	_ = types.BloomLookup
	_ = event.NewSubscription
)
const ApproveAndCallFallBackABI = "[{\"constant\":false,\"inputs\":[{\"name\":\"from\",\"type\":\"address\"},{\"name\":\"tokens\",\"type\":\"uint256\"},{\"name\":\"token\",\"type\":\"address\"},{\"name\":\"data\",\"type\":\"bytes\"}],\"name\":\"receiveApproval\",\"outputs\":[],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"}]"
const ApproveAndCallFallBackBin = `0x`
func DeployApproveAndCallFallBack(auth *bind.TransactOpts, backend bind.ContractBackend) (common.Address, *types.Transaction, *ApproveAndCallFallBack, error) {
	parsed, err := abi.JSON(strings.NewReader(ApproveAndCallFallBackABI))
	if err != nil {
		return common.Address{}, nil, nil, err
	}
	address, tx, contract, err := bind.DeployContract(auth, parsed, common.FromHex(ApproveAndCallFallBackBin), backend)
	if err != nil {
		return common.Address{}, nil, nil, err
	}
	return address, tx, &ApproveAndCallFallBack{ApproveAndCallFallBackCaller: ApproveAndCallFallBackCaller{contract: contract}, ApproveAndCallFallBackTransactor: ApproveAndCallFallBackTransactor{contract: contract}, ApproveAndCallFallBackFilterer: ApproveAndCallFallBackFilterer{contract: contract}}, nil
}
type ApproveAndCallFallBack struct {
	ApproveAndCallFallBackCaller      
	ApproveAndCallFallBackTransactor  
	ApproveAndCallFallBackFilterer    
}
type ApproveAndCallFallBackCaller struct {
	contract *bind.BoundContract  
}
type ApproveAndCallFallBackTransactor struct {
	contract *bind.BoundContract  
}
type ApproveAndCallFallBackFilterer struct {
	contract *bind.BoundContract  
}
type ApproveAndCallFallBackSession struct {
	Contract     *ApproveAndCallFallBack  
	CallOpts     bind.CallOpts            
	TransactOpts bind.TransactOpts        
}
type ApproveAndCallFallBackCallerSession struct {
	Contract *ApproveAndCallFallBackCaller  
	CallOpts bind.CallOpts                  
}
type ApproveAndCallFallBackTransactorSession struct {
	Contract     *ApproveAndCallFallBackTransactor  
	TransactOpts bind.TransactOpts                  
}
type ApproveAndCallFallBackRaw struct {
	Contract *ApproveAndCallFallBack  
}
type ApproveAndCallFallBackCallerRaw struct {
	Contract *ApproveAndCallFallBackCaller  
}
type ApproveAndCallFallBackTransactorRaw struct {
	Contract *ApproveAndCallFallBackTransactor  
}
func NewApproveAndCallFallBack(address common.Address, backend bind.ContractBackend) (*ApproveAndCallFallBack, error) {
	contract, err := bindApproveAndCallFallBack(address, backend, backend, backend)
	if err != nil {
		return nil, err
	}
	return &ApproveAndCallFallBack{ApproveAndCallFallBackCaller: ApproveAndCallFallBackCaller{contract: contract}, ApproveAndCallFallBackTransactor: ApproveAndCallFallBackTransactor{contract: contract}, ApproveAndCallFallBackFilterer: ApproveAndCallFallBackFilterer{contract: contract}}, nil
}
func NewApproveAndCallFallBackCaller(address common.Address, caller bind.ContractCaller) (*ApproveAndCallFallBackCaller, error) {
	contract, err := bindApproveAndCallFallBack(address, caller, nil, nil)
	if err != nil {
		return nil, err
	}
	return &ApproveAndCallFallBackCaller{contract: contract}, nil
}
func NewApproveAndCallFallBackTransactor(address common.Address, transactor bind.ContractTransactor) (*ApproveAndCallFallBackTransactor, error) {
	contract, err := bindApproveAndCallFallBack(address, nil, transactor, nil)
	if err != nil {
		return nil, err
	}
	return &ApproveAndCallFallBackTransactor{contract: contract}, nil
}
func NewApproveAndCallFallBackFilterer(address common.Address, filterer bind.ContractFilterer) (*ApproveAndCallFallBackFilterer, error) {
	contract, err := bindApproveAndCallFallBack(address, nil, nil, filterer)
	if err != nil {
		return nil, err
	}
	return &ApproveAndCallFallBackFilterer{contract: contract}, nil
}
func bindApproveAndCallFallBack(address common.Address, caller bind.ContractCaller, transactor bind.ContractTransactor, filterer bind.ContractFilterer) (*bind.BoundContract, error) {
	parsed, err := abi.JSON(strings.NewReader(ApproveAndCallFallBackABI))
	if err != nil {
		return nil, err
	}
	return bind.NewBoundContract(address, parsed, caller, transactor, filterer), nil
}
func (_ApproveAndCallFallBack *ApproveAndCallFallBackRaw) Call(opts *bind.CallOpts, result interface{}, method string, params ...interface{}) error {
	return _ApproveAndCallFallBack.Contract.ApproveAndCallFallBackCaller.contract.Call(opts, result, method, params...)
}
func (_ApproveAndCallFallBack *ApproveAndCallFallBackRaw) Transfer(opts *bind.TransactOpts) (*types.Transaction, error) {
	return _ApproveAndCallFallBack.Contract.ApproveAndCallFallBackTransactor.contract.Transfer(opts)
}
func (_ApproveAndCallFallBack *ApproveAndCallFallBackRaw) Transact(opts *bind.TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
	return _ApproveAndCallFallBack.Contract.ApproveAndCallFallBackTransactor.contract.Transact(opts, method, params...)
}
func (_ApproveAndCallFallBack *ApproveAndCallFallBackCallerRaw) Call(opts *bind.CallOpts, result interface{}, method string, params ...interface{}) error {
	return _ApproveAndCallFallBack.Contract.contract.Call(opts, result, method, params...)
}
func (_ApproveAndCallFallBack *ApproveAndCallFallBackTransactorRaw) Transfer(opts *bind.TransactOpts) (*types.Transaction, error) {
	return _ApproveAndCallFallBack.Contract.contract.Transfer(opts)
}
func (_ApproveAndCallFallBack *ApproveAndCallFallBackTransactorRaw) Transact(opts *bind.TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
	return _ApproveAndCallFallBack.Contract.contract.Transact(opts, method, params...)
}
func (_ApproveAndCallFallBack *ApproveAndCallFallBackTransactor) ReceiveApproval(opts *bind.TransactOpts, from common.Address, tokens *big.Int, token common.Address, data []byte) (*types.Transaction, error) {
	return _ApproveAndCallFallBack.contract.Transact(opts, "receiveApproval", from, tokens, token, data)
}
func (_ApproveAndCallFallBack *ApproveAndCallFallBackSession) ReceiveApproval(from common.Address, tokens *big.Int, token common.Address, data []byte) (*types.Transaction, error) {
	return _ApproveAndCallFallBack.Contract.ReceiveApproval(&_ApproveAndCallFallBack.TransactOpts, from, tokens, token, data)
}
func (_ApproveAndCallFallBack *ApproveAndCallFallBackTransactorSession) ReceiveApproval(from common.Address, tokens *big.Int, token common.Address, data []byte) (*types.Transaction, error) {
	return _ApproveAndCallFallBack.Contract.ReceiveApproval(&_ApproveAndCallFallBack.TransactOpts, from, tokens, token, data)
}
const ERC20InterfaceABI = "[{\"constant\":false,\"inputs\":[{\"name\":\"spender\",\"type\":\"address\"},{\"name\":\"tokens\",\"type\":\"uint256\"}],\"name\":\"approve\",\"outputs\":[{\"name\":\"success\",\"type\":\"bool\"}],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"totalSupply\",\"outputs\":[{\"name\":\"\",\"type\":\"uint256\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"name\":\"from\",\"type\":\"address\"},{\"name\":\"to\",\"type\":\"address\"},{\"name\":\"tokens\",\"type\":\"uint256\"}],\"name\":\"transferFrom\",\"outputs\":[{\"name\":\"success\",\"type\":\"bool\"}],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[{\"name\":\"tokenOwner\",\"type\":\"address\"}],\"name\":\"balanceOf\",\"outputs\":[{\"name\":\"balance\",\"type\":\"uint256\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"name\":\"to\",\"type\":\"address\"},{\"name\":\"tokens\",\"type\":\"uint256\"}],\"name\":\"transfer\",\"outputs\":[{\"name\":\"success\",\"type\":\"bool\"}],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[{\"name\":\"tokenOwner\",\"type\":\"address\"},{\"name\":\"spender\",\"type\":\"address\"}],\"name\":\"allowance\",\"outputs\":[{\"name\":\"remaining\",\"type\":\"uint256\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":true,\"name\":\"from\",\"type\":\"address\"},{\"indexed\":true,\"name\":\"to\",\"type\":\"address\"},{\"indexed\":false,\"name\":\"tokens\",\"type\":\"uint256\"}],\"name\":\"Transfer\",\"type\":\"event\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":true,\"name\":\"tokenOwner\",\"type\":\"address\"},{\"indexed\":true,\"name\":\"spender\",\"type\":\"address\"},{\"indexed\":false,\"name\":\"tokens\",\"type\":\"uint256\"}],\"name\":\"Approval\",\"type\":\"event\"}]"
const ERC20InterfaceBin = `0x`
func DeployERC20Interface(auth *bind.TransactOpts, backend bind.ContractBackend) (common.Address, *types.Transaction, *ERC20Interface, error) {
	parsed, err := abi.JSON(strings.NewReader(ERC20InterfaceABI))
	if err != nil {
		return common.Address{}, nil, nil, err
	}
	address, tx, contract, err := bind.DeployContract(auth, parsed, common.FromHex(ERC20InterfaceBin), backend)
	if err != nil {
		return common.Address{}, nil, nil, err
	}
	return address, tx, &ERC20Interface{ERC20InterfaceCaller: ERC20InterfaceCaller{contract: contract}, ERC20InterfaceTransactor: ERC20InterfaceTransactor{contract: contract}, ERC20InterfaceFilterer: ERC20InterfaceFilterer{contract: contract}}, nil
}
type ERC20Interface struct {
	ERC20InterfaceCaller      
	ERC20InterfaceTransactor  
	ERC20InterfaceFilterer    
}
type ERC20InterfaceCaller struct {
	contract *bind.BoundContract  
}
type ERC20InterfaceTransactor struct {
	contract *bind.BoundContract  
}
type ERC20InterfaceFilterer struct {
	contract *bind.BoundContract  
}
type ERC20InterfaceSession struct {
	Contract     *ERC20Interface    
	CallOpts     bind.CallOpts      
	TransactOpts bind.TransactOpts  
}
type ERC20InterfaceCallerSession struct {
	Contract *ERC20InterfaceCaller  
	CallOpts bind.CallOpts          
}
type ERC20InterfaceTransactorSession struct {
	Contract     *ERC20InterfaceTransactor  
	TransactOpts bind.TransactOpts          
}
type ERC20InterfaceRaw struct {
	Contract *ERC20Interface  
}
type ERC20InterfaceCallerRaw struct {
	Contract *ERC20InterfaceCaller  
}
type ERC20InterfaceTransactorRaw struct {
	Contract *ERC20InterfaceTransactor  
}
func NewERC20Interface(address common.Address, backend bind.ContractBackend) (*ERC20Interface, error) {
	contract, err := bindERC20Interface(address, backend, backend, backend)
	if err != nil {
		return nil, err
	}
	return &ERC20Interface{ERC20InterfaceCaller: ERC20InterfaceCaller{contract: contract}, ERC20InterfaceTransactor: ERC20InterfaceTransactor{contract: contract}, ERC20InterfaceFilterer: ERC20InterfaceFilterer{contract: contract}}, nil
}
func NewERC20InterfaceCaller(address common.Address, caller bind.ContractCaller) (*ERC20InterfaceCaller, error) {
	contract, err := bindERC20Interface(address, caller, nil, nil)
	if err != nil {
		return nil, err
	}
	return &ERC20InterfaceCaller{contract: contract}, nil
}
func NewERC20InterfaceTransactor(address common.Address, transactor bind.ContractTransactor) (*ERC20InterfaceTransactor, error) {
	contract, err := bindERC20Interface(address, nil, transactor, nil)
	if err != nil {
		return nil, err
	}
	return &ERC20InterfaceTransactor{contract: contract}, nil
}
func NewERC20InterfaceFilterer(address common.Address, filterer bind.ContractFilterer) (*ERC20InterfaceFilterer, error) {
	contract, err := bindERC20Interface(address, nil, nil, filterer)
	if err != nil {
		return nil, err
	}
	return &ERC20InterfaceFilterer{contract: contract}, nil
}
func bindERC20Interface(address common.Address, caller bind.ContractCaller, transactor bind.ContractTransactor, filterer bind.ContractFilterer) (*bind.BoundContract, error) {
	parsed, err := abi.JSON(strings.NewReader(ERC20InterfaceABI))
	if err != nil {
		return nil, err
	}
	return bind.NewBoundContract(address, parsed, caller, transactor, filterer), nil
}
func (_ERC20Interface *ERC20InterfaceRaw) Call(opts *bind.CallOpts, result interface{}, method string, params ...interface{}) error {
	return _ERC20Interface.Contract.ERC20InterfaceCaller.contract.Call(opts, result, method, params...)
}
func (_ERC20Interface *ERC20InterfaceRaw) Transfer(opts *bind.TransactOpts) (*types.Transaction, error) {
	return _ERC20Interface.Contract.ERC20InterfaceTransactor.contract.Transfer(opts)
}
func (_ERC20Interface *ERC20InterfaceRaw) Transact(opts *bind.TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
	return _ERC20Interface.Contract.ERC20InterfaceTransactor.contract.Transact(opts, method, params...)
}
func (_ERC20Interface *ERC20InterfaceCallerRaw) Call(opts *bind.CallOpts, result interface{}, method string, params ...interface{}) error {
	return _ERC20Interface.Contract.contract.Call(opts, result, method, params...)
}
func (_ERC20Interface *ERC20InterfaceTransactorRaw) Transfer(opts *bind.TransactOpts) (*types.Transaction, error) {
	return _ERC20Interface.Contract.contract.Transfer(opts)
}
func (_ERC20Interface *ERC20InterfaceTransactorRaw) Transact(opts *bind.TransactOpts, method string, params ...interface{}) (*types.Transaction, error) {
	return _ERC20Interface.Contract.contract.Transact(opts, method, params...)
}
func (_ERC20Interface *ERC20InterfaceCaller) Allowance(opts *bind.CallOpts, tokenOwner common.Address, spender common.Address) (*big.Int, error) {
	var (
		ret0 = new(*big.Int)
	)
	out := ret0
	err := _ERC20Interface.contract.Call(opts, out, "allowance", tokenOwner, spender)
	return *ret0, err
}
func (_ERC20Interface *ERC20InterfaceSession) Allowance(tokenOwner common.Address, spender common.Address) (*big.Int, error) {
	return _ERC20Interface.Contract.Allowance(&_ERC20Interface.CallOpts, tokenOwner, spender)
}
func (_ERC20Interface *ERC20InterfaceCallerSession) Allowance(tokenOwner common.Address, spender common.Address) (*big.Int, error) {
	return _ERC20Interface.Contract.Allowance(&_ERC20Interface.CallOpts, tokenOwner, spender)
}
func (_ERC20Interface *ERC20InterfaceCaller) BalanceOf(opts *bind.CallOpts, tokenOwner common.Address) (*big.Int, error) {
	var (
		ret0 = new(*big.Int)
	)
	out := ret0
	err := _ERC20Interface.contract.Call(opts, out, "balanceOf", tokenOwner)
	return *ret0, err
}
func (_ERC20Interface *ERC20InterfaceSession) BalanceOf(tokenOwner common.Address) (*big.Int, error) {
	return _ERC20Interface.Contract.BalanceOf(&_ERC20Interface.CallOpts, tokenOwner)
}
func (_ERC20Interface *ERC20InterfaceCallerSession) BalanceOf(tokenOwner common.Address) (*big.Int, error) {
	return _ERC20Interface.Contract.BalanceOf(&_ERC20Interface.CallOpts, tokenOwner)
}
func (_ERC20Interface *ERC20InterfaceCaller) TotalSupply(opts *bind.CallOpts) (*big.Int, error) {
	var (
		ret0 = new(*big.Int)
	)
	out := ret0
	err := _ERC20Interface.contract.Call(opts, out, "totalSupply")
	return *ret0, err
}
func (_ERC20Interface *ERC20InterfaceSession) TotalSupply() (*big.Int, error) {
	return _ERC20Interface.Contract.TotalSupply(&_ERC20Interface.CallOpts)
}
func (_ERC20Interface *ERC20InterfaceCallerSession) TotalSupply() (*big.Int, error) {
	return _ERC20Interface.Contract.TotalSupply(&_ERC20Interface.CallOpts)
}
func (_ERC20Interface *ERC20InterfaceTransactor) Approve(opts *bind.TransactOpts, spender common.Address, tokens *big.Int) (*types.Transaction, error) {
	return _ERC20Interface.contract.Transact(opts, "approve", spender, tokens)
}
func (_ERC20Interface *ERC20InterfaceSession) Approve(spender common.Address, tokens *big.Int) (*types.Transaction, error) {
	return _ERC20Interface.Contract.Approve(&_ERC20Interface.TransactOpts, spender, tokens)
}
func (_ERC20Interface *ERC20InterfaceTransactorSession) Approve(spender common.Address, tokens *big.Int) (*types.Transaction, error) {
	return _ERC20Interface.Contract.Approve(&_ERC20Interface.TransactOpts, spender, tokens)
}
func (_ERC20Interface *ERC20InterfaceTransactor) Transfer(opts *bind.TransactOpts, to common.Address, tokens *big.Int) (*types.Transaction, error) {
	return _ERC20Interface.contract.Transact(opts, "transfer", to, tokens)
}
func (_ERC20Interface *ERC20InterfaceSession) Transfer(to common.Address, tokens *big.Int) (*types.Transaction, error) {
	return _ERC20Interface.Contract.Transfer(&_ERC20Interface.TransactOpts, to, tokens)
}
func (_ERC20Interface *ERC20InterfaceTransactorSession) Transfer(to common.Address, tokens *big.Int) (*types.Transaction, error) {
	return _ERC20Interface.Contract.Transfer(&_ERC20Interface.TransactOpts, to, tokens)
}
func (_ERC20Interface *ERC20InterfaceTransactor) TransferFrom(opts *bind.TransactOpts, from common.Address, to common.Address, tokens *big.Int) (*types.Transaction, error) {
	return _ERC20Interface.contract.Transact(opts, "transferFrom", from, to, tokens)
}
func (_ERC20Interface *ERC20InterfaceSession) TransferFrom(from common.Address, to common.Address, tokens *big.Int) (*types.Transaction, error) {
	return _ERC20Interface.Contract.TransferFrom(&_ERC20Interface.TransactOpts, from, to, tokens)
}
func (_ERC20Interface *ERC20InterfaceTransactorSession) TransferFrom(from common.Address, to common.Address, tokens *big.Int) (*types.Transaction, error) {
	return _ERC20Interface.Contract.TransferFrom(&_ERC20Interface.TransactOpts, from, to, tokens)
}
type ERC20InterfaceApprovalIterator struct {
	Event *ERC20InterfaceApproval  
	contract *bind.BoundContract  
	event    string               
	logs chan types.Log         
	sub  ethereum.Subscription  
	done bool                   
	fail error                  
}
func (it *ERC20InterfaceApprovalIterator) Next() bool {
	if it.fail != nil {
		return false
	}
	if it.done {
		select {
		case log := <-it.logs:
			it.Event = new(ERC20InterfaceApproval)
			if err := it.contract.UnpackLog(it.Event, it.event, log); err != nil {
				it.fail = err
				return false
			}
			it.Event.Raw = log
			return true
		default:
			return false
		}
	}
	select {
	case log := <-it.logs:
		it.Event = new(ERC20InterfaceApproval)
		if err := it.contract.UnpackLog(it.Event, it.event, log); err != nil {
			it.fail = err
			return false
		}
		it.Event.Raw = log
		return true
	case err := <-it.sub.Err():
		it.done = true
		it.fail = err
		return it.Next()
	}
}
func (it *ERC20InterfaceApprovalIterator) Error() error {
	return it.fail
}
func (it *ERC20InterfaceApprovalIterator) Close() error {
	it.sub.Unsubscribe()
	return nil
}
type ERC20InterfaceApproval struct {
	TokenOwner common.Address
	Spender    common.Address
	Tokens     *big.Int
	Raw        types.Log  
}
func (_ERC20Interface *ERC20InterfaceFilterer) FilterApproval(opts *bind.FilterOpts, tokenOwner []common.Address, spender []common.Address) (*ERC20InterfaceApprovalIterator, error) {
	var tokenOwnerRule []interface{}
	for _, tokenOwnerItem := range tokenOwner {
		tokenOwnerRule = append(tokenOwnerRule, tokenOwnerItem)
	}
	var spenderRule []interface{}
	for _, spenderItem := range spender {
		spenderRule = append(spenderRule, spenderItem)
	}
	logs, sub, err := _ERC20Interface.contract.FilterLogs(opts, "Approval", tokenOwnerRule, spenderRule)
	if err != nil {
		return nil, err
	}
	return &ERC20InterfaceApprovalIterator{contract: _ERC20Interface.contract, event: "Approval", logs: logs, sub: sub}, nil
}