code: def gen_lines(self, block, indent):
          
          prefix1 = indent + self.PS1
          prefix2 = indent + self.PS2
          prefix = prefix1
          for line in block:
              if line.startswith(prefix):
                  yield line[len(prefix):]
              elif line == prefix.rstrip() + u"\n":
                  yield u"\n"
              else:
                  raise AssertionError("line=%r, prefix=%r" % (line, prefix))
              prefix = prefix2
          while True:
              yield ""
docs: Generates lines as expected by tokenize from a list of lines.
  
          This strips the first len(indent + self.PS1) characters off each line.