#NEWLINE# def LB( self , k ) : #NEWLINE# #INDENT# 'Look backwards k tokens on-channel tokens' #NEWLINE# if ( self . p == ( - 1 ) ) : #NEWLINE# #INDENT# self . fillBuffer ( ) #NEWLINE# #UNINDENT# if ( k == 0 ) : #NEWLINE# #INDENT# return None #NEWLINE# #UNINDENT# if ( ( self . p - k ) < 0 ) : #NEWLINE# #INDENT# return None #NEWLINE# #UNINDENT# i = self . p #NEWLINE# n = 1 #NEWLINE# while ( n <= k ) : #NEWLINE# #INDENT# i = self . skipOffTokenChannelsReverse ( ( i - 1 ) ) #NEWLINE# n += 1 #NEWLINE# #UNINDENT# if ( i < 0 ) : #NEWLINE# #INDENT# return None #NEWLINE# #UNINDENT# return self . tokens [ i ]