def is_odd(digit):
    if digit % 2 != 0:
        return True

    return False 

digits = [
    1, 7, 18, 2, 4, 2, 8, 5, 3
    ]

digits

[1, 7, 18, 2, 4, 2, 8, 5, 3]

new_list = list(filter(lambda x: is_odd(x) , digits))

new_list

[1, 7, 5, 3]