func (k Keeper) SetUnbondingDelegation(ctx sdk.Context, ubd types.UnbondingDelegation) {
	store := ctx.KVStore(k.storeKey)
	bz := types.MustMarshalUBD(k.cdc, ubd)
	key := types.GetUBDKey(ubd.DelegatorAddress, ubd.ValidatorAddress)
	store.Set(key, bz)
	store.Set(types.GetUBDByValIndexKey(ubd.DelegatorAddress, ubd.ValidatorAddress), []byte{})  
}
set the unbonding delegation and associated index
package keeper
import (
	"bytes"
	"fmt"
	"time"
	"github.com/Dipper-Labs/Dipper-Protocol/app/v0/staking/types"
	sdk "github.com/Dipper-Labs/Dipper-Protocol/types"
	sdkerrors "github.com/Dipper-Labs/Dipper-Protocol/types/errors"
)
func (k Keeper) GetDelegation(ctx sdk.Context,
	delAddr sdk.AccAddress, valAddr sdk.ValAddress) (
	delegation types.Delegation, found bool) {
	store := ctx.KVStore(k.storeKey)
	key := types.GetDelegationKey(delAddr, valAddr)
	value := store.Get(key)
	if value == nil {
		return delegation, false
	}
	delegation = types.MustUnmarshalDelegation(k.cdc, value)
	return delegation, true
}
func (k Keeper) IterateAllDelegations(ctx sdk.Context, cb func(delegation types.Delegation) (stop bool)) {
	store := ctx.KVStore(k.storeKey)
	iterator := sdk.KVStorePrefixIterator(store, types.DelegationKey)
	defer iterator.Close()
	for ; iterator.Valid(); iterator.Next() {
		delegation := types.MustUnmarshalDelegation(k.cdc, iterator.Value())
		if cb(delegation) {
			break
		}
	}
}
func (k Keeper) GetAllDelegations(ctx sdk.Context) (delegations []types.Delegation) {
	k.IterateAllDelegations(ctx, func(delegation types.Delegation) bool {
		delegations = append(delegations, delegation)
		return false
	})
	return delegations
}
func (k Keeper) GetValidatorDelegations(ctx sdk.Context, valAddr sdk.ValAddress) (delegations []types.Delegation) {
	store := ctx.KVStore(k.storeKey)
	iterator := sdk.KVStorePrefixIterator(store, types.DelegationKey)
	defer iterator.Close()
	for ; iterator.Valid(); iterator.Next() {
		delegation := types.MustUnmarshalDelegation(k.cdc, iterator.Value())
		if delegation.GetValidatorAddr().Equals(valAddr) {
			delegations = append(delegations, delegation)
		}
	}
	return delegations
}
func (k Keeper) GetDelegatorDelegations(ctx sdk.Context, delegator sdk.AccAddress,
	maxRetrieve uint16) (delegations []types.Delegation) {
	delegations = make([]types.Delegation, maxRetrieve)
	store := ctx.KVStore(k.storeKey)
	delegatorPrefixKey := types.GetDelegationsKey(delegator)
	iterator := sdk.KVStorePrefixIterator(store, delegatorPrefixKey)
	defer iterator.Close()
	i := 0
	for ; iterator.Valid() && i < int(maxRetrieve); iterator.Next() {
		delegation := types.MustUnmarshalDelegation(k.cdc, iterator.Value())
		delegations[i] = delegation
		i++
	}
	return delegations[:i]  
}
func (k Keeper) SetDelegation(ctx sdk.Context, delegation types.Delegation) {
	store := ctx.KVStore(k.storeKey)
	b := types.MustMarshalDelegation(k.cdc, delegation)
	store.Set(types.GetDelegationKey(delegation.DelegatorAddress, delegation.ValidatorAddress), b)
}
func (k Keeper) RemoveDelegation(ctx sdk.Context, delegation types.Delegation) {
	k.BeforeDelegationRemoved(ctx, delegation.DelegatorAddress, delegation.ValidatorAddress)
	store := ctx.KVStore(k.storeKey)
	store.Delete(types.GetDelegationKey(delegation.DelegatorAddress, delegation.ValidatorAddress))
}
func (k Keeper) GetUnbondingDelegations(ctx sdk.Context, delegator sdk.AccAddress,
	maxRetrieve uint16) (unbondingDelegations []types.UnbondingDelegation) {
	unbondingDelegations = make([]types.UnbondingDelegation, maxRetrieve)
	store := ctx.KVStore(k.storeKey)
	delegatorPrefixKey := types.GetUBDsKey(delegator)
	iterator := sdk.KVStorePrefixIterator(store, delegatorPrefixKey)
	defer iterator.Close()
	i := 0
	for ; iterator.Valid() && i < int(maxRetrieve); iterator.Next() {
		unbondingDelegation := types.MustUnmarshalUBD(k.cdc, iterator.Value())
		unbondingDelegations[i] = unbondingDelegation
		i++
	}
	return unbondingDelegations[:i]  
}
func (k Keeper) GetUnbondingDelegation(ctx sdk.Context,
	delAddr sdk.AccAddress, valAddr sdk.ValAddress) (ubd types.UnbondingDelegation, found bool) {
	store := ctx.KVStore(k.storeKey)
	key := types.GetUBDKey(delAddr, valAddr)
	value := store.Get(key)
	if value == nil {
		return ubd, false
	}
	ubd = types.MustUnmarshalUBD(k.cdc, value)
	return ubd, true
}
func (k Keeper) GetUnbondingDelegationsFromValidator(ctx sdk.Context, valAddr sdk.ValAddress) (ubds []types.UnbondingDelegation) {
	store := ctx.KVStore(k.storeKey)
	iterator := sdk.KVStorePrefixIterator(store, types.GetUBDsByValIndexKey(valAddr))
	defer iterator.Close()
	for ; iterator.Valid(); iterator.Next() {
		key := types.GetUBDKeyFromValIndexKey(iterator.Key())
		value := store.Get(key)
		ubd := types.MustUnmarshalUBD(k.cdc, value)
		ubds = append(ubds, ubd)
	}
	return ubds
}
func (k Keeper) IterateUnbondingDelegations(ctx sdk.Context, fn func(index int64, ubd types.UnbondingDelegation) (stop bool)) {
	store := ctx.KVStore(k.storeKey)
	iterator := sdk.KVStorePrefixIterator(store, types.UnbondingDelegationKey)
	defer iterator.Close()
	for i := int64(0); iterator.Valid(); iterator.Next() {
		ubd := types.MustUnmarshalUBD(k.cdc, iterator.Value())
		if stop := fn(i, ubd); stop {
			break
		}
		i++
	}
}
func (k Keeper) HasMaxUnbondingDelegationEntries(ctx sdk.Context,
	delegatorAddr sdk.AccAddress, validatorAddr sdk.ValAddress) bool {
	ubd, found := k.GetUnbondingDelegation(ctx, delegatorAddr, validatorAddr)
	if !found {
		return false
	}
	return len(ubd.Entries) >= int(k.MaxEntries(ctx))
}