code: function Assignment(param, requisition) {
      this.param = param;
      this.requisition = requisition;
      this.setValue(param.defaultValue);
  }
docs: A link between a parameter and the data for that parameter.
  The data for the parameter is available as in the preferred type and as
  an Argument for the CLI.
  <p>We also record validity information where applicable.
  <p>For values, null and undefined have distinct definitions. null means
  that a value has been provided, undefined means that it has not.
  Thus, null is a valid default value, and common because it identifies an
  parameter that is optional. undefined means there is no value from
  the command line.
  @constructor