class_docstr: Optional base class for fixers.
  
  The subclass name must be FixFooBar where FooBar is the result of
  removing underscores and capitalizing the words of the fix name.
  For example, the class name for a fixer named 'has_key' should be
  FixHasKey.
class_docstr_tok: ["Optional","base","class","for","fixers",".","The","subclass","name","must","be","FixFooBar","where","FooBar","is","the","result","of","removing","underscores","and","capitalizing","the","words","of","the","fix","name",".","For","example",",","the","class","name","for","a","fixer","named","'has_key","'","should","be","FixHasKey","."]
docstr: Warn the user that a given chunk of code is not valid Python 3,
  but that it cannot be converted automatically.
  
  First argument is the top-level node for the code in question.
  Optional second argument is why it can't be converted.
docstr_tok: ["Warn","the","user","that","a","given","chunk","of","code","is","not","valid","Python","3",",","but","that","it","can","not","be","converted","automatically",".","First","argument","is","the","top-level","node","for","the","code","in","question",".","Optional","second","argument","is","why","it","ca","n't","be","converted","."]
code: def cannot_convert(self, node, reason=None):
      """Warn the user that a given chunk of code is not valid Python 3,
      but that it cannot be converted automatically.
  
      First argument is the top-level node for the code in question.
      Optional second argument is why it can't be converted.
      """
      lineno = node.get_lineno()
      for_output = node.clone()
      for_output.prefix = ""
      msg = "Line %d: could not convert: %s"
      self.log_message(msg % (lineno, for_output))
      if reason:
          self.log_message(reason)
  
imports: import itertools
  from .patcomp import PatternCompiler
  from .None import pygram
  from .fixer_util import does_tree_import
label_desc: Use image node_id 8 for calling the BaseFix obj's underlying member method code with example usage: obj.cannot_convert(node, reason) without return types