text: import pytest
  
  from web3.utils.blocks import (
      is_predefined_block_number,
  )
  
  
  @pytest.mark.parametrize(
      'block_identifier,expected',
      (
          ('earliest', True),
          ('latest', True),
          ('pending', True),
          (1, False),
          ('0x1', False),
      ),
  )
  def test_is_predefined_block_number(block_identifier, expected):
      actual = is_predefined_block_number(block_identifier)
      assert actual is expected
  