func (s sliceResults) Keys() []string {
	panic("Cannot get map keys from Slice")
}
Not supported by sliceResults
package async
type Results interface {
	Index(int) []interface{}   
	Key(string) []interface{}  
	Len() int                  
	Keys() []string            
}
type sliceResults [][]interface{}
func (s sliceResults) Index(i int) []interface{} {
	return s[i]
}
func (s sliceResults) Len() int {
	return len(s)
}