code: def asSubForm(self, name):
          
          self.subFormName = name
          self.jsClass = _SUBFORM_JS_CLASS
          return self
docs: Make a form suitable for nesting within another form (a subform) out
          of this top-level liveform.
  
          @param name: the name of the subform within its parent.
          @type name: C{unicode}
  
          @return: a subform.
          @rtype: L{LiveForm}