docstr: Test streamlit.string_util.is_emoji.
code: def test_is_emoji(self, text: str, expected: bool):
      """Test streamlit.string_util.is_emoji."""
      self.assertEqual(string_util.is_emoji(text), expected)
  
file_path: streamlit/lib/tests/streamlit/string_util_test.py
imports: import unittest
  from parameterized import parameterized
  from streamlit import string_util
label_desc: Use image node_id 2 for calling the StringUtilTest obj's underlying member method code with example usage: obj.test_is_emoji(text, expected) without return types