code: def exists(val):
      return val is not None
  
file_path: performer-pytorch/performer_pytorch/autoregressive_wrapper.py
imports: from functools import partial
  import torch
  from torch import nn
  import torch.nn.functional
  from torch.nn.utils.rnn import pad_sequence
label_desc: Use image node_id 1 for calling a global function with example usage: exists(val) and returns: unknown