docs: def f_extend_old(map, s):
      """Extend map of function to cover sphere "twice" up to theta=2pi
  
      This introduces new points when Nphi is odd, and duplicates values when Nphi is even, making it
      easier to perform certain transformation operations.
  
      This is mostly an internal function, included here for backwards compatibility.  See map2salm
      and salm2map for more useful functions.
  
      """
      import numpy as np
      map = np.ascontiguousarray(map, dtype=np.complex128)
      extended_map = np.empty((2*(map.shape[0]-1), map.shape[1],), dtype=np.complex128)
      _f_extend_old(map, extended_map, s)
      return extended_map