code: func fromString(att *design.AttributeDefinition, varName string) string {
  	switch att.Type.Kind() {
  	case design.BooleanKind:
  		return "strconv.ParseBool(" + varName + ")"
  	case design.IntegerKind:
  		return "strconv.Atoi(" + varName + ")"
  	case design.NumberKind:
  		return "strconv.ParseFloat(" + varName + ")"
  	case design.StringKind:
  		return varName + ", (error)(nil)"
  	case design.ArrayKind:
  	case design.HashKind:
  		return valueTypeOf("", att) + "{}, (error)(nil)"
  	}
  	return "(" + valueTypeOf("", att) + ")(nil), (error)(nil)"
  }
docs: // fromString returns the gocode expression to convert string typed varName value to go-type defined in the attribute