code: def erf(tensor):
      r"""
      Approximates the error function of the input tensor using a Taylor approximation.
      """
      iters = cfg.safety.mpc.functions.erf_iterations
  
      output = tensor.clone()
      for n in range(1, iters + 1):
          multiplier = ((-1) ** n) / (math.factorial(n) * (2 * n + 1))
          output = output.add(tensor.pos_pow(2 * n + 1).mul(multiplier))
      return output.mul(2.0 / math.sqrt(math.pi))
  
imports: import math
  import torch
  from fate.arch.protocol import mpc
  from ..common.util import chebyshev_series
  from ..config import cfg
label_desc: Use image node_id 13 for calling a global function with example usage: erf(tensor) and returns: output