def METHOD_NAME(self, index):
    """
    Retrieves the presence status of power supply unit (PSU) defined
            by 1-based index <index>
    :param index: An integer, 1-based index of the PSU of which to query status
    :return: Boolean, True if PSU is plugged, False if not
    """
    if index is None:
        raise RuntimeError("index shouldn't be None")
    if index > self.MAX_NUM_PSU:
        raise RuntimeError("index ({}) shouldn't be greater than {}".format(index, self.MAX_NUM_PSU))
    status = self._read_file(self.psu_presence, index)
    return status == 1