code: def test_ishashable():
      class C:
          pass
  
      assert ishashable("x")
      assert ishashable(1)
      assert ishashable(C())
      assert ishashable((1, 2))
      assert not ishashable([1, 2])
      assert not ishashable({1: 2})
  
imports: from __future__ import annotations
  import pickle
  from collections import namedtuple
  import pytest
  from dask.core import flatten, get, get_dependencies, get_deps, getcycle, has_tasks, ishashable, iskey, istask, literal, preorder_traversal, quote, subs, validate_key
  from dask.utils_test import GetFunctionTestMixin, add, inc
label_desc: Use image node_id 2 for calling a global function with example usage: test_ishashable() without return types