code: def to_array(self, itaper, normalization='4pi', csphase=1):
          
          if type(normalization) != str:
              raise ValueError('normalization must be a string. ' +
                               'Input type was {:s}'
                               .format(str(type(normalization))))
  
          if normalization.lower() not in ('4pi', 'ortho', 'schmidt'):
              raise ValueError(
                  "normalization must be '4pi', 'ortho' " +
                  "or 'schmidt'. Provided value was {:s}"
                  .format(repr(normalization))
                  )
          if csphase != 1 and csphase != -1:
              raise ValueError(
                  "csphase must be 1 or -1. Input value was {:s}"
                  .format(repr(csphase))
                  )
  
          return self._to_array(
              itaper, normalization=normalization.lower(), csphase=csphase)
docs: Return the spherical harmonic coefficients of taper i as a numpy
          array.
  
          Usage
          -----
          coeffs = x.to_array(itaper, [normalization, csphase])
  
          Returns
          -------
          coeffs : ndarray, shape (2, lwin+1, lwin+11)
              3-D numpy ndarray of the spherical harmonic coefficients of the
              window.
  
          Parameters
          ----------
          itaper : int
              Taper number, where itaper=0 is the best concentrated.
          normalization : str, optional, default = '4pi'
              Normalization of the output coefficients: '4pi', 'ortho' or
              'schmidt' for geodesy 4pi normalized, orthonormalized, or Schmidt
              semi-normalized coefficients, respectively.
          csphase : int, optional, default = 1
              Condon-Shortley phase convention: 1 to exclude the phase factor,
              or -1 to include it.