func (c Continue) Fuzz(obj interface{}) {
	v := reflect.ValueOf(obj)
	if v.Kind() != reflect.Ptr {
		panic("needed ptr!")
	}
	v = v.Elem()
	c.fc.doFuzz(v, 0)
}
Fuzz continues fuzzing obj. obj must be a pointer.
package fuzz
import (
	"fmt"
	"math/rand"
	"reflect"
	"time"
)
type fuzzFuncMap map[reflect.Type]reflect.Value
type Fuzzer struct {
	fuzzFuncs        fuzzFuncMap
	defaultFuzzFuncs fuzzFuncMap
	r                *rand.Rand
	nilChance        float64
	minElements      int
	maxElements      int
	maxDepth         int
}
func New() *Fuzzer {
	return NewWithSeed(time.Now().UnixNano())
}
func NewWithSeed(seed int64) *Fuzzer {
	f := &Fuzzer{
		defaultFuzzFuncs: fuzzFuncMap{
			reflect.TypeOf(&time.Time{}): reflect.ValueOf(fuzzTime),
		},
		fuzzFuncs:   fuzzFuncMap{},
		r:           rand.New(rand.NewSource(seed)),
		nilChance:   .2,
		minElements: 1,
		maxElements: 10,
		maxDepth:    100,
	}
	return f
}
func (f *Fuzzer) Funcs(fuzzFuncs ...interface{}) *Fuzzer {
	for i := range fuzzFuncs {
		v := reflect.ValueOf(fuzzFuncs[i])
		if v.Kind() != reflect.Func {
			panic("Need only funcs!")
		}
		t := v.Type()
		if t.NumIn() != 2 || t.NumOut() != 0 {
			panic("Need 2 in and 0 out params!")
		}
		argT := t.In(0)
		switch argT.Kind() {
		case reflect.Ptr, reflect.Map:
		default:
			panic("fuzzFunc must take pointer or map type")
		}
		if t.In(1) != reflect.TypeOf(Continue{}) {
			panic("fuzzFunc's second parameter must be type fuzz.Continue")
		}
		f.fuzzFuncs[argT] = v
	}
	return f
}
func (f *Fuzzer) RandSource(s rand.Source) *Fuzzer {
	f.r = rand.New(s)
	return f
}
func (f *Fuzzer) NilChance(p float64) *Fuzzer {
	if p < 0 || p > 1 {
		panic("p should be between 0 and 1, inclusive.")
	}
	f.nilChance = p
	return f
}
func (f *Fuzzer) NumElements(atLeast, atMost int) *Fuzzer {
	if atLeast > atMost {
		panic("atLeast must be <= atMost")
	}
	if atLeast < 0 {
		panic("atLeast must be >= 0")
	}
	f.minElements = atLeast
	f.maxElements = atMost
	return f
}
func (f *Fuzzer) genElementCount() int {
	if f.minElements == f.maxElements {
		return f.minElements
	}
	return f.minElements + f.r.Intn(f.maxElements-f.minElements+1)
}
func (f *Fuzzer) genShouldFill() bool {
	return f.r.Float64() > f.nilChance
}
func (f *Fuzzer) MaxDepth(d int) *Fuzzer {
	f.maxDepth = d
	return f
}
func (f *Fuzzer) Fuzz(obj interface{}) {
	v := reflect.ValueOf(obj)
	if v.Kind() != reflect.Ptr {
		panic("needed ptr!")
	}
	v = v.Elem()
	f.fuzzWithContext(v, 0)
}
func (f *Fuzzer) FuzzNoCustom(obj interface{}) {
	v := reflect.ValueOf(obj)
	if v.Kind() != reflect.Ptr {
		panic("needed ptr!")
	}
	v = v.Elem()
	f.fuzzWithContext(v, flagNoCustomFuzz)
}
const (
	flagNoCustomFuzz uint64 = 1 << iota
)
func (f *Fuzzer) fuzzWithContext(v reflect.Value, flags uint64) {
	fc := &fuzzerContext{fuzzer: f}
	fc.doFuzz(v, flags)
}
type fuzzerContext struct {
	fuzzer   *Fuzzer
	curDepth int
}
func (fc *fuzzerContext) doFuzz(v reflect.Value, flags uint64) {
	if fc.curDepth >= fc.fuzzer.maxDepth {
		return
	}
	fc.curDepth++
	defer func() { fc.curDepth-- }()
	if !v.CanSet() {
		return
	}
	if flags&flagNoCustomFuzz == 0 {
		if v.CanAddr() && fc.tryCustom(v.Addr()) {
			return
		}
		if fc.tryCustom(v) {
			return
		}
	}
	if fn, ok := fillFuncMap[v.Kind()]; ok {
		fn(v, fc.fuzzer.r)
		return
	}
	switch v.Kind() {
	case reflect.Map:
		if fc.fuzzer.genShouldFill() {
			v.Set(reflect.MakeMap(v.Type()))
			n := fc.fuzzer.genElementCount()
			for i := 0; i < n; i++ {
				key := reflect.New(v.Type().Key()).Elem()
				fc.doFuzz(key, 0)
				val := reflect.New(v.Type().Elem()).Elem()
				fc.doFuzz(val, 0)
				v.SetMapIndex(key, val)
			}
			return
		}
		v.Set(reflect.Zero(v.Type()))
	case reflect.Ptr:
		if fc.fuzzer.genShouldFill() {
			v.Set(reflect.New(v.Type().Elem()))
			fc.doFuzz(v.Elem(), 0)
			return
		}
		v.Set(reflect.Zero(v.Type()))
	case reflect.Slice:
		if fc.fuzzer.genShouldFill() {
			n := fc.fuzzer.genElementCount()
			v.Set(reflect.MakeSlice(v.Type(), n, n))
			for i := 0; i < n; i++ {
				fc.doFuzz(v.Index(i), 0)
			}
			return
		}
		v.Set(reflect.Zero(v.Type()))
	case reflect.Array:
		if fc.fuzzer.genShouldFill() {
			n := v.Len()
			for i := 0; i < n; i++ {
				fc.doFuzz(v.Index(i), 0)
			}
			return
		}
		v.Set(reflect.Zero(v.Type()))
	case reflect.Struct:
		for i := 0; i < v.NumField(); i++ {
			fc.doFuzz(v.Field(i), 0)
		}
	case reflect.Chan:
		fallthrough
	case reflect.Func:
		fallthrough
	case reflect.Interface:
		fallthrough
	default:
		panic(fmt.Sprintf("Can't handle %#v", v.Interface()))
	}
}
func (fc *fuzzerContext) tryCustom(v reflect.Value) bool {
	doCustom, ok := fc.fuzzer.fuzzFuncs[v.Type()]
	if !ok {
		if v.CanInterface() {
			intf := v.Interface()
			if fuzzable, ok := intf.(Interface); ok {
				fuzzable.Fuzz(Continue{fc: fc, Rand: fc.fuzzer.r})
				return true
			}
		}
		doCustom, ok = fc.fuzzer.defaultFuzzFuncs[v.Type()]
		if !ok {
			return false
		}
	}
	switch v.Kind() {
	case reflect.Ptr:
		if v.IsNil() {
			if !v.CanSet() {
				return false
			}
			v.Set(reflect.New(v.Type().Elem()))
		}
	case reflect.Map:
		if v.IsNil() {
			if !v.CanSet() {
				return false
			}
			v.Set(reflect.MakeMap(v.Type()))
		}
	default:
		return false
	}
	doCustom.Call([]reflect.Value{v, reflect.ValueOf(Continue{
		fc:   fc,
		Rand: fc.fuzzer.r,
	})})
	return true
}
type Interface interface {
	Fuzz(c Continue)
}
type Continue struct {
	fc *fuzzerContext
	*rand.Rand
}