class_docstr: Coupling Block following the NICE design.
code: def forward(self, x, c=[], rev=False):
      x1, x2 = (x[:, :, : self.split_len1], x[:, :, self.split_len1 :])
      if not rev:
          x2_c = torch.cat([x2, *c], 1) if self.conditional else x2
          y1 = x1 + self.F(x2_c)
          y1_c = torch.cat([y1, *c], 1) if self.conditional else y1
          y2 = x2 + self.G(y1_c)
      else:
          x1_c = torch.cat([x1, *c], 1) if self.conditional else x1
          y2 = x2 - self.G(x1_c)
          y2_c = torch.cat([y2, *c], 1) if self.conditional else y2
          y1 = x1 - self.F(y2_c)
  
      return torch.cat((y1, y2), -1)
  
imports: import math
  import torch
  from torch import nn
  from transformers.activations import get_activation
  from ..configuration import AdapterFusionConfig, BnConfig
  from ..context import ForwardContext
label_desc: Use image node_id 2 for calling the NICECouplingBlock obj's underlying member method code with example usage: obj.forward(x, c, rev) and returns: torch