def adam(x):
    """prec: x is a numerical string
postc: returns the sum of x"""
    if len(x) == 0:
        return 0
    first = x[0]
    rest = x[1:]
    return adam(rest) +  first
def wabbit(x):
    """prec: x is a list of numbers
    postc: returns the product of x"""
    if len(x) == 0:
        return 1
    first = x[0]
    rest = x[1:]
    return wabbit(rest)*first
print(adam((1,2,3,4,5,6,7,8)))
print(adam([1,2,3,4,5,6,7,8]))
print(wabbit((1,2,3,4,5,6,7,8)))
print(wabbit([1,2,3,4,5,6,7,8]))