'Open a standard format marker file for sequential reading.
:param sfm_file: name of the standard format marker input file
:type sfm_file: str'

def open(self, sfm_file):

    if isinstance(sfm_file, PathPointer):
        self._file = sfm_file.open(self._encoding)
    else:
        self._file = codecs.open(sfm_file, 'rU', self._encoding)
