######################Problem 2###########################
def filter_sum(s):
    """prec: s is a string
    postc:  the total of all digits in the string is returned."""
    out = 0
    for ch in s:
        if ch.isdigit():
            out += int(ch)
    return out
def filter_sum(s):
    """prec: s is a string
    postc:  the total of all digits in the string is returned."""
    out = 0
    for ch in s:
        if ch in "0123456789":
            out += int(ch)
    return out
def filter_sum(s):
    return sum([int(k) for k in s if k.isdigit()])
def main():
    print("*************** Problem 2 Tests **************")
    print(filter_sum("c1o2w3s4moo") ==  10)
main()