'Open the file stream associated with this corpus view.  This
will be called performed if any value is read from the view
while its file stream is closed.'

def _open(self):

    if isinstance(self._fileid, PathPointer):
        self._stream = self._fileid.open(self._encoding)
    elif self._encoding:
        self._stream = SeekableUnicodeStreamReader(open(self._fileid, 'rb'), self._encoding)
    else:
        self._stream = open(self._fileid, 'rb')
