#NEWLINE# def test_subset( self ) : #NEWLINE# #INDENT# 'subset should return set of leaves that descends from node' #NEWLINE# t = self . simple_t #NEWLINE# self . assertEqual ( t . subset ( ) , frozenset ( 'abcd' ) ) #NEWLINE# c = t . children [ 0 ] #NEWLINE# self . assertEqual ( c . subset ( ) , frozenset ( 'ab' ) ) #NEWLINE# leaf = c . children [ 1 ] #NEWLINE# self . assertEqual ( leaf . subset ( ) , frozenset ( '' ) )