<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_solar_flux(self, band):
 """Get the solar flux for the band."""

        solar_flux = self.cal['solar_flux'].isel(bands=band).values
        d_index = self.cal['detector_index'].fillna(0).astype(int)

        return da.map_blocks(self._get_items, d_index.data, solar_flux=solar_flux, dtype=solar_flux.dtype)