def choose(n, k):
    """ Binomial coefficients
    Return the n!/((n-k)!k!)

    Arguments:
        n -- Integer
        k -- Integer

    Returns:
        The bionomial coefficient n choose k

    Example:
      >>> choose(6,2)
      15

    """
    ntok = 1
    for t in range(min(k, n - k)):
        ntok = ntok * (n - t) // (t + 1)
    return ntok