code: def _to_array(self, alpha, normalization='4pi', csphase=1):
          
          coeffs = _shtools.SHVectorToCilm(self.tapers[:, alpha])
  
          if normalization == 'schmidt':
              for l in range(self.lmax + 1):
                  coeffs[:, l, :l+1] *= _np.sqrt(2.0 * l + 1.0)
          elif normalization == 'ortho':
              coeffs *= _np.sqrt(4.0 * _np.pi)
  
          if csphase == -1:
              for m in range(self.lmax + 1):
                  if m % 2 == 1:
                      coeffs[:, :, m] = - coeffs[:, :, m]
  
          return coeffs
docs: Return the spherical harmonic coefficients of Slepian function i as an
          array, where i=0 is the best concentrated function.