code: def exists(val):
      return val is not None
  
imports: import torch
  import torch.nn.functional
  from torch import nn
  from vit_pytorch.vit import ViT
  from vit_pytorch.t2t import T2TViT
  from vit_pytorch.efficient import ViT
  from einops import rearrange, repeat
label_desc: Use image node_id 1 for calling a global function with example usage: exists(val) and returns: unknown