code: def clone(self, default):
          
          return self.__class__(
              self.name,
              self.type,
              self.coercer,
              self.label,
              self.description,
              default,
              self.viewFactory)
docs: Make a copy of this parameter, supplying a different default.
  
          @type default: C{unicode} or C{NoneType}
          @param default: A value which will be initially presented in the view
          as the value for this parameter, or C{None} if no such value is to be
          presented.
  
          @rtype: L{Parameter}