# Tutorial code from Prof. Peter Wentworth

# Rhodes University, South Africa (http://www.ru.ac.za/)

def sumList(xs):

'''

Sum a list that can contain nested lists.

Precondition: All leaf elements are numbers.

'''

sum = 0

for e in xs:

if type(e) is list:

print("Calling sumList(%s) recursively" % e)

v = sumList(e)

print("sumList(%s) returned %s" % (e, v))

sum += v

else:

sum += e

return sum

testData = [10, [20, 30, [40], 50], 60]

print("Calling sumList(%s)" % testData)

result = sumList(testData)

print("Final sum of all numbers in initial list is %s" % result)