<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_stddevs(self, C, stddev_types, nsites):
 """ Compute total standard deviation, see table 4.2, page 50. """

        stddevs = []
        for stddev_type in stddev_types:
            assert stddev_type in self.DEFINED_FOR_STANDARD_DEVIATION_TYPES
            if stddev_type == const.StdDev.TOTAL:
                stddevs.append(C['sigma'] + np.zeros(nsites, dtype=float))
        return stddevs