(self, filename)
This private class method checks if the given `filename` has the proper
        `extension` set in the child class. If not it raises a ValueError.

        :param string filename: file to check.
This private class method checks if the given `filename` has the proper
        `extension` set in the child class. If not it raises a ValueError.
This private class method checks if the given filename has the proper extension set in the child class . If not it raises a ValueError .
def _check_extension(self, filename):
        """
        This private class method checks if the given `filename` has the proper
        `extension` set in the child class. If not it raises a ValueError.

        :param string filename: file to check.
        """
        __, file_ext = os.path.splitext(filename)
        if file_ext not in self.extensions:
            raise ValueError(
                'The input file does not have the proper extension. \
                It is {0!s}, instead of {1!s}.'.format(file_ext,
                                                       self.extensions))
def _check_extension ( self , filename ) : __ , file_ext = os . path . splitext ( filename ) if file_ext not in self . extensions : raise ValueError ( 'The input file does not have the proper extension. \
                It is {0!s}, instead of {1!s}.' . format ( file_ext , self . extensions ) )