docstr: torch.sign does not support complex numbers.
docstr_tok: ["torch.sign","does","not","support","complex","numbers","."]
code: def sign(tensor):
      """torch.sign does not support complex numbers."""
      return torch.sgn(tensor)
  
imports: from packaging.version import Version
  import numpy
  from .core import Backend, backend_types, backend_basic_math, backend_array
label_desc: Use image node_id 28 for calling the PyTorchBackend obj's underlying member method code with example usage: obj.sign(tensor) and returns: torch