gistfile1.py

def alternates_even_odd(x):
    x = iter(x)
    try:
        while True:
            if next(x)%2:
                return False
            if not next(x)%2:
                return False
    except StopIteration:
        return True

def check(expected, sequence):
    actual = alternates_even_odd(sequence)
    print(actual)
    if alternates_even_odd(sequence) is not expected:
        print('fuck', sequence)

check(True, [0, 1, 2, 3])
check(False, [0, 1, 3, 2])
check(True, [])
check(False, [4, 7, 5])