code: def group_lines(self, input):
      lex = self.lexer.clone()
      lines = [x.rstrip() for x in input.splitlines()]
      for i in xrange(len(lines)):
          j = i + 1
          while lines[i].endswith("\\") and (j < len(lines)):
              lines[i] = lines[i][:-1] + lines[j]
              lines[j] = ""
              j += 1
  
      input = "\n".join(lines)
      lex.input(input)
      lex.lineno = 1
  
      current_line = []
      while True:
          tok = lex.token()
          if not tok:
              break
          current_line.append(tok)
          if tok.type in self.t_WS and "\n" in tok.value:
              yield current_line
              current_line = []
  
      if current_line:
          yield current_line
  
imports: import sys
  import re
  import copy
  import time
  import os.path
label_desc: Use image node_id 6 for calling the Preprocessor obj's underlying member method code with example usage: obj.group_lines(input) without return types