def prod(*x):
    """
    Returns the product of elements, just like built-in function `sum`.
    
    Example:
    ----------
    >>> prod([5, 2, 1, 4, 2])
    80
    """
    if len(x) == 1 and isinstance(x[0], list): x = x[0]
    p = 1
    for i in x: 
        if hasattr(i, "__mul__"):
            p *= i
    return p