package main import ( "fmt" ) type echo struct { } func (f *echo) Validate(args []interface{}) error{ if len(args) != 1{ return fmt.Errorf("echo function only supports 1 parameter but got %d", len(args)) } return nil } func (f *echo) Exec(args []interface{}) (interface{}, bool) { result := args[0] return result, true } func (f *echo) IsAggregate() bool { return false } var Echo echo