code: def _make_real(self, check=True):
          
          # Test if the coefficients correspond to a real grid.
          # This is not very elegant, and the equality condition
          # is probably not robust to round off errors.
          if check:
              for l in self.degrees():
                  if self.coeffs[0, l, 0] != self.coeffs[0, l, 0].conjugate():
                      raise RuntimeError('Complex coefficients do not ' +
                                         'correspond to a real field. ' +
                                         'l = {:d}, m = 0: {:e}'
                                         .format(l, self.coeffs[0, l, 0]))
                  for m in _np.arange(1, l + 1):
                      if m % 2 == 1:
                          if (self.coeffs[0, l, m] != -
                                  self.coeffs[1, l, m].conjugate()):
                              raise RuntimeError('Complex coefficients do not ' +
                                                 'correspond to a real field. ' +
                                                 'l = {:d}, m = {:d}: {:e}, {:e}'
                                                 .format(
                                                     l, m, self.coeffs[0, l, 0],
                                                     self.coeffs[1, l, 0]))
                      else:
                          if (self.coeffs[0, l, m] !=
                                  self.coeffs[1, l, m].conjugate()):
                              raise RuntimeError('Complex coefficients do not ' +
                                                 'correspond to a real field. ' +
                                                 'l = {:d}, m = {:d}: {:e}, {:e}'
                                                 .format(
                                                     l, m, self.coeffs[0, l, 0],
                                                     self.coeffs[1, l, 0]))
  
          coeffs_rc = _np.zeros((2, self.lmax + 1, self.lmax + 1))
          coeffs_rc[0, :, :] = self.coeffs[0, :, :].real
          coeffs_rc[1, :, :] = self.coeffs[0, :, :].imag
          real_coeffs = _shtools.SHctor(coeffs_rc, convention=1,
                                        switchcs=0)
          return SHCoeffs.from_array(real_coeffs,
                                     normalization=self.normalization,
                                     csphase=self.csphase)
docs: Convert the complex SHCoeffs class to the real class.