code: def log2(x):
      """Implementatin of Log2. Pytorch doesn't have a native implemenation."""
      ln2 = Variable(
          torch.log(torch.FloatTensor([2.0])), requires_grad=False
      )
      if x.is_cuda:
          ln2 = ln2.cuda()
      return torch.log(x) / ln2
  
imports: import numpy
  import scipy.misc
  import scipy.ndimage
  import torch
  from torch.autograd import Variable
  import torch.nn
label_desc: Use image node_id 20 for calling a global function with example usage: log2(x) and returns: unknown