def check_split_cell(cell_string):
    """Will return tuple of floats a, b, c, alpha, beta, gamma from input
    cell string which contains a,b,c,alpha,beta,gamma raising an exception
    if there is a problem."""

    ideal_string = "a,b,c,alpha,beta,gamma"

    if not cell_string.count(",") == 5:
        raise RuntimeError("%s should be of the form %s" % (cell_string, ideal_string))

    a, b, c, alpha, beta, gamma = tuple(map(float, cell_string.split(",")))

    return a, b, c, alpha, beta, gamma