code: def altzeta(ctx, s, **kwargs):
      try:
          return ctx._altzeta(s, **kwargs)
      except NotImplementedError:
          return ctx._altzeta_generic(s)
  
imports: from __future__ import print_function
  from ..libmp.backend import xrange
  from .functions import defun, defun_wrapped, defun_static
label_desc: Use image node_id 21 for calling a global function with example usage: altzeta(ctx, s) and returns: ctx, ctx