code: function(xmlElement) {
      var value = xmlElement.getAttribute('value');
      this.hasReturnValue_ = (value == 1);
      if (!this.hasReturnValue_) {
        this.removeInput('VALUE');
        this.appendDummyInput('VALUE')
          .appendField(Blockly.Msg.PROCEDURES_DEFRETURN_RETURN);
      }
    }
docs: Parse XML to restore whether this block has a return value.
  @param {!Element} xmlElement XML storage element.
  @this Blockly.Block