import unittest

from collections import Counter
def has_palindrome_permutation(the_string):
    counter = Counter(the_string)
    return len([freq for freq in counter.values() if freq % 2 == 1]) <= 1

# Tests
class Test(unittest.TestCase):

    def test_permutation_with_odd_number_of_chars(self):
        result = has_palindrome_permutation('aabcbcd')
        self.assertTrue(result)

    def test_permutation_with_even_number_of_chars(self):
        result = has_palindrome_permutation('aabccbdd')
        self.assertTrue(result)

    def test_no_permutation_with_odd_number_of_chars(self):
        result = has_palindrome_permutation('aabcd')
        self.assertFalse(result)

    def test_no_permutation_with_even_number_of_chars(self):
        result = has_palindrome_permutation('aabbcd')
        self.assertFalse(result)

    def test_empty_string(self):
        result = has_palindrome_permutation('')
        self.assertTrue(result)

    def test_one_character_string(self):
        result = has_palindrome_permutation('a')
        self.assertTrue(result)

unittest.main(verbosity=2)
