def _open_file(self, mode, encoding=None):
if self._filename[-<NUM_LIT:4>:] == '<STR_LIT>':<EOL><INDENT>self._file = bz2.open(self._filename, mode=mode, encoding=encoding)<EOL><DEDENT>else:<EOL><INDENT>self._file = open(self._filename, mode=mode, encoding=encoding)<EOL><DEDENT>
Opens the next current file.

:param str mode: The mode for opening the file.
:param str encoding: The encoding of the file.