Make a random array of shape (len(dates), len(sids)) with ``dtype``.

def values(self, dtype, dates, sids):
        """
        Make a random array of shape (len(dates), len(sids)) with ``dtype``.
        """
        shape = (len(dates), len(sids))
        return {
            datetime64ns_dtype: self._datetime_values,
            float64_dtype: self._float_values,
            int64_dtype: self._int_values,
            bool_dtype: self._bool_values,
            object_dtype: self._object_values,
        }[dtype](shape)