def test_node_get_index(self):
"""
Test TrieNode._get_index static method
"""
# test lowercase letters
for i, letter in enumerate(string.ascii_lowercase):
index = TrieNode._get_index(letter)
self.assertEqual(i, index)
# test uppercase letters
for i, letter in enumerate(string.ascii_uppercase):
index = TrieNode._get_index(letter)
self.assertEqual(i, index)
