class_docstr: Base class for a model description.
  
  It is used for the simple training interface described in
  `Training Interface Tutorial <https://tensorpack.readthedocs.io/tutorial/training-interface.html>`_.
  
  Subclass is expected to implement :meth:`inputs` and :meth:`build_graph`, as they
  together define a tower function.
docstr: list[str]: the names of all the inputs.
docstr_tok: ["list","[","str","]",":","the","names","of","all","the","inputs","."]
code: def input_names(self):
      """
      list[str]: the names of all the inputs.
      """
      return [k.name for k in self.get_input_signature()]
  
file_path: tensorpack/tensorpack/train/model_desc.py
imports: import tensorflow
  from ..utils.argtools import memoized_method
  from ..tfutils.common import get_op_tensor_name
  from ..tfutils.tower import get_current_tower_context
  from ..compat import _backport_tensor_spec, tfv1
label_desc: Use image node_id 2 for calling the ModelDescBase obj's underlying member method code with example usage: obj.input_names() and returns: unknown