docstr: Test an error is raised when using a function with varargs.
code: def test_layer_stack_no_varargs(self):
      """Test an error is raised when using a function with varargs."""
  
      class VarArgsModule(module.Module):
          """When used, this module should cause layer_stack to raise an Error."""
  
          def __call__(self, *args):
              return args
  
      class NoVarArgsModule(module.Module):
          """This module should be fine to use with layer_stack."""
  
          def __call__(self, x):
              return x
  
      def build_and_init_stack(module_class):
          def stack_fn(x):
              mod = module_class()
              return layer_stack.layer_stack(1)(mod)(x)
  
          stack = multi_transform.without_apply_rng(
              transform.transform(stack_fn)
          )
          stack.init(jax.random.PRNGKey(1729), jnp.ones([5]))
  
      build_and_init_stack(NoVarArgsModule)
      with self.assertRaisesRegex(
          ValueError, "The function `f` should not have any `varargs`"
      ):
          build_and_init_stack(VarArgsModule)
  
imports: import functools
  import re
  from typing import Optional
  from absl.testing import absltest
  from absl.testing import parameterized
  from haiku._src import base
  from haiku._src import basic
  from haiku._src import config
  from haiku._src import initializers
  from haiku._src import layer_stack
  from haiku._src import module
  from haiku._src import multi_transform
  from haiku._src import transform
  from haiku._src import utils
  import jax
  import jax.numpy
  import numpy
  from scipy import stats
label_desc: Use image node_id 5 for calling the LayerStackTest obj's underlying member method code with example usage: obj.test_layer_stack_no_varargs() and returns: args, x, layer_stack