code: def tokenstrip(self, tokens):
      i = 0
      while i < len(tokens) and tokens[i].type in self.t_WS:
          i += 1
      del tokens[:i]
      i = len(tokens) - 1
      while i >= 0 and tokens[i].type in self.t_WS:
          i -= 1
      del tokens[i + 1 :]
      return tokens
  
imports: import sys
  import re
  import copy
  import time
  import os.path
label_desc: Use image node_id 7 for calling the Preprocessor obj's underlying member method code with example usage: obj.tokenstrip(tokens) and returns: tokens