func (c BaseCollection) ToStruct(dist interface{}) {
	panic("not implement")
}
ToStruct turn the collection to the specified struct using mapstructure.
https://github.com/mitchellh/mapstructure
package collection
import (
	"encoding/json"
	"github.com/shopspring/decimal"
)
type BaseCollection struct {
	value  interface{}
	length int
}
func (c BaseCollection) Value() interface{} {
	return c.value
}
func (c BaseCollection) Length() int {
	return c.length
}
func (c BaseCollection) Select(keys ...string) Collection {
	panic("not implement")
}