code: def getlines(filename, module_globals=None):
      
  
      if filename in cache:
          return cache[filename][2]
  
      try:
          return updatecache(filename, module_globals)
      except MemoryError:
          clearcache()
          return []
docs: Get the lines for a file from the cache.
      Update the cache if it doesn't contain an entry for this file already.