def divide(x, y):
    """
    Divides two floats where the second must be non-zero, otherwise a
    ZeroDivisionError is raise.

    :type x: float
    :param x: numerator
    :type y: float != 0
    :param y: denominator
    :rtype: float
    """
    if y != 0:
        return x / y
    else:
        raise ZeroDivisionError