(self, source, name, filename=None)
return source
This method is called before the actual lexing and can be used to
        preprocess the source.  The `filename` is optional.  The return value
        must be the preprocessed source.
This method is called before the actual lexing and can be used to
        preprocess the source.  The `filename` is optional.  The return value
        must be the preprocessed source.
This method is called before the actual lexing and can be used to preprocess the source . The filename is optional . The return value must be the preprocessed source .
def preprocess(self, source, name, filename=None):
        """This method is called before the actual lexing and can be used to
        preprocess the source.  The `filename` is optional.  The return value
        must be the preprocessed source.
        """
        return source
def preprocess ( self , source , name , filename = None ) : return source