code: def cat(
      seq: Sequence[Union[ComplexTensor, torch.Tensor]], *args, **kwargs
  ):
      if not isinstance(seq, (list, tuple)):
          raise TypeError(
              "cat(): argument 'tensors' (position 1) must be tuple of Tensors, "
              "not Tensor"
          )
      if isinstance(seq[0], ComplexTensor):
          return FC.cat(seq, *args, **kwargs)
      else:
          return torch.cat(seq, *args, **kwargs)
  
file_path: espnet/espnet2/enh/layers/complex_utils.py
imports: from typing import Sequence, Tuple, Union
  import torch
  from torch_complex import functional
  from torch_complex.tensor import ComplexTensor
label_desc: Use image node_id 7 for calling a global function with example usage: cat(seq) and returns: FC, torch