code: func (method Method) Sig() string {
  	types := make([]string, len(method.Inputs))
  	for i, input := range method.Inputs {
  		types[i] = input.Type.String()
  	}
  	return fmt.Sprintf("%v(%v)", method.Name, strings.Join(types, ","))
  }
docs: // Sig returns the methods string signature according to the ABI spec.
  //
  // Example
  //
  //     function foo(uint32 a, int b)    =    "foo(uint32,int256)"
  //
  // Please note that "int" is substitute for its canonical representation "int256"