def determine_left_shift(five_prime, indel, three_prime):
    """
    Adjust 5' and 3' context of indel such that
    indel is fully shifted to 5'

    Args:
        five_prime (string) : Five prime sequence
        indel (string) : Sequence of indel
        three_prime (string) : Three prime sequence

    Returns:
        (string, string) : New sequence of 5' and 3' sequences
    """
    while five_prime.endswith(indel):
        five_prime = five_prime[:-len(indel)]
        three_prime = indel + three_prime
    # may have not fully shifted homopolymer
    while len(indel) * five_prime[-1] == indel:
        three_prime = five_prime[-1] + three_prime
        five_prime = five_prime[:-1]
    return (five_prime, three_prime)