message: Fix description of input specs in assert_input_compatibility
diff: @@ -133,8 +133,10 @@ def assert_input_compatibility(input_spec, inputs, layer_name):
  of a layer (if any). If not, a clear and actional exception gets raised.
  Arguments:
  - input_spec: An InputSpec instance, or None.
  - inputs: Input tensor or list of input tensors.
  + input_spec: An InputSpec instance, list of InputSpec instances, a nested
  + structure of InputSpec instances, or None.
  + inputs: Input tensor, list of input tensors, or a nested structure of
  + input tensors.
  layer_name: String, name of the layer (for error message formatting).
  Raises:
  