def purify_1(numbers):
    even = []
    for number in range(len(numbers)):
        if numbers[number] % 2 == 0:
            even.append(numbers[number])
    return even

def purify_2(numbers):
    even = []
    for number in numbers:
        if number % 2 == 0:
            even.append(number)
    return even

print (purify_1([1,2,3]))
print (purify_2([1,2,3,4,5,6]))