code: def exists(val):
      return val is not None
  
imports: from functools import partial
  import torch
  from torch import nn, einsum
  import torch.nn.functional
  from torch.nn import Module, ModuleList, Sequential
  from einops import rearrange, repeat, reduce, pack, unpack
  from einops.layers.torch import Rearrange, Reduce
label_desc: Use image node_id 1 for calling a global function with example usage: exists(val) and returns: unknown