code: def attribute_exists(self, name):
          
  
          if name in self:
              if issubclass(self[name].__class__, Attribute):
                  return True
          return False
docs: Returns if given attribute exists in the node.
  
          Usage::
  
              >>>	node_a = AbstractNode("MyNodeA", attributeA=Attribute(), attributeB=Attribute())
              >>> node_a.attribute_exists("attributeA")
              True
              >>> node_a.attribute_exists("attributeC")
              False
  
          :param name: Attribute name.
          :type name: unicode
          :return: Attribute exists.
          :rtype: bool