def __contains__(self, key):
node = self.get_node(key)<EOL>if node is not None:<EOL><INDENT>name = node._v_pathname<EOL>if name == key or name[<NUM_LIT:1>:] == key:<EOL><INDENT>return True<EOL><DEDENT><DEDENT>return False<EOL>
check for existence of this key
              can match the exact pathname or the pathnm w/o the leading '/'