def test_t():
assert main.complementary('T') == 'A'
def test_a():
assert main.complementary('A') == 'T'
def test_c():
assert main.complementary('C') == 'G'
def test_complete():
assert main.complementary('ATGC') == 'TACG'
def test_g():
assert main.complementary('G') == 'C'