code: def log_t(u, t):
      """Compute log_t for `u'."""
      if t == 1.0:
          return u.log()
      else:
          return (u.pow(1.0 - t) - 1.0) / (1.0 - t)
  
imports: from typing import Optional
  import torch
  from torch import nn, Tensor
label_desc: Use image node_id 1 for calling a global function with example usage: log_t(u, t) and returns: u, unknown