def hamming_distance(p, q):
    """Calculate the HammingDistance for two strings. We say that position i in k-mers p and q is a mismatch if the symbols at position i of the two strings are not the same. The total number of mismatches between strings p and q is called the Hamming distance between these strings. We will let you implement a function to compute this distance, called HammingDistance(p, q).

    Args:
        p (str): the first DNA string.
        q (str): the second DNA string, p and q of the equal length.

    Returns:
        Integer, number of different base count between p and q, i.e. the Hamming distance between these strings.

    Examples:
        Solving the Hamming distance of two DNA Genomes.

        >>> p = 'GGGCCGTTGGT'
        >>> q = 'GGACCGTTGAC'
        >>> hammingdistance = hamming_distance(p, q)
        >>> hammingdistance
            3
    """
    count = 0
    for i in range(len(p)):
        if p[i] != q[i]:
            count += 1
    return count