"can only concatenate tuple"?

[wlsa]

The question wants me to create a function that takes a tuple as an input, and returns a new tuple as an output, where every other element of the input tuple is copied, starting with the first element.

def oddTuples(aTup):
    i=0
    what_I_want=()
    while i<len(aTup):
        if i%2==0:
            final=final + aTup[i]
        i+=1
    print(what_I_want)
oddTuples((1, 2, 3, 4 ,5,))

expected output: (1, 3, 5)
actual output: typeError: can only concatenate tuple (not "int") to tuple
I'm confused about the basis of the question because I learned a tuple is immutable so how could I do this?