code: def extract_transformers_from_source(source):
      '''Scan a source for lines of the form
         from __experimental__ import transformer1 [,...]
         identifying transformers to be used. Such line is passed to the
         add_transformer function, after which it is removed from the
         code to be executed.
      '''
      lines = source.split('\n')
      linenumbers = []
      for number, line in enumerate(lines):
          if FROM_EXPERIMENTAL.match(line):
              add_transformers(line)
              linenumbers.insert(0, number)
  
      # drop the "fake" import from the source code
      for number in linenumbers:
          del lines[number]
      return '\n'.join(linesf extract_transformers_from_source(source):
      '''Scan a source for lines of the form
         from __experimental__ import transformer1 [,...]
         identifying transformers to be used. Such line is passed to the
         add_transformer function, after which it is removed from the
         code to be executed.
      '''
      lines = source.split('\n')
      linenumbers = []
      for number, line in enumerate(lines):
          if FROM_EXPERIMENTAL.match(line):
              add_transformers(line)
              linenumbers.insert(0, number)
  
      # drop the "fake" import from the source code
      for number in linenumbers:
          del lines[number]
      return '\n'.join(lines)
docs: Scan a source for lines of the form
         from __experimental__ import transformer1 [,...]
         identifying transformers to be used. Such line is passed to the
         add_transformer function, after which it is removed from the
         code to be executed.