code: def polylog_series(ctx, s, z):
      tol = +ctx.eps
      l = ctx.zero
      k = 1
      zk = z
      while 1:
          term = zk / k**s
          l += term
          if abs(term) < tol:
              break
          zk *= z
          k += 1
      return l
  
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 14 for calling a global function with example usage: polylog_series(ctx, s, z) and returns: l