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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _read_from_buffer(self, pos: int) -> None: """Attempts to complete the currently-pending read from the buffer. The argument is either a position in the read buffer or None, as returned by _find_read_pos. """

        self._read_bytes = self._read_delimiter = self._read_regex = None
        self._read_partial = False
        self._finish_read(pos, False)