def bfs(self, root = None, display = None):
        '''
        API: bfs(self, root = None, display = None)
        Description:
            Searches tree starting from node named root using breadth-first
            strategy if root argument is provided. Starts search from root node
            of the tree otherwise.
        Pre:
            Node indicated by root argument should exist.
        Input:
            root: Starting node name.
            display: Display argument.
        '''
        if root == None:
            root = self.root
        if display == None:
            display = self.attr['display']
        self.traverse(root, display, Queue())
def bfs ( self , root = None , display = None ) : if root == None : root = self . root if display == None : display = self . attr [ 'display' ] self . traverse ( root , display , Queue ( ) )
API: bfs(self, root = None, display = None)
        Description:
            Searches tree starting from node named root using breadth-first
            strategy if root argument is provided. Starts search from root node
            of the tree otherwise.
        Pre:
            Node indicated by root argument should exist.
        Input:
            root: Starting node name.
            display: Display argument.