def _L(dfs_data):
"""<STR_LIT>"""<EOL>node_set = set()<EOL>for v, adj in list(dfs_data['<STR_LIT>'].items()):<EOL><INDENT>w = adj[<NUM_LIT:0>]<EOL>if is_frond(v, w, dfs_data):<EOL><INDENT>node_set.add(v)<EOL><DEDENT><DEDENT>return list(node_set)<EOL>
L(T) contains leaves and branch points for the DFS-tree T.