:param vector_a:    A list of numbers.
    :param vector_b:    A list of numbers.
    :returns:           The euclidean distance between the two vectors.

def _euclidean_dist(vector_a, vector_b):
    """
    :param vector_a:    A list of numbers.
    :param vector_b:    A list of numbers.
    :returns:           The euclidean distance between the two vectors.
    """
    dist = 0
    for (x, y) in zip(vector_a, vector_b):
        dist += (x-y)*(x-y)
    return math.sqrt(dist)