code: def test_elementary_axis_name(self) -> None:
      for name in [
          "a",
          "b",
          "h",
          "dx",
          "h1",
          "zz",
          "i9123",
          "somelongname",
          "Alex",
          "camelCase",
          "u_n_d_e_r_score",
          "unreasonablyLongAxisName",
      ]:
          self.assertTrue(ParsedExpression.check_axis_name(name))
  
      for name in [
          "",
          "2b",
          "12",
          "_startWithUnderscore",
          "endWithUnderscore_",
          "_",
          "...",
          _ellipsis,
      ]:
          self.assertFalse(ParsedExpression.check_axis_name(name))
  
imports: from typing import Any, Callable, Dict
  from unittest import mock
  from functorch.einops._parsing import AnonymousAxis, ParsedExpression, parse_pattern, validate_rearrange_expressions, _ellipsis
  from torch.testing._internal.common_utils import TestCase, run_tests
label_desc: Use image node_id 1 for calling the TestParsedExpression obj's underlying member method code with example usage: obj.test_elementary_axis_name() without return types