Python Cannot Return Multiple Values

It is often said that Python functions can return multiple values, but this isn't really true. Often the examples given to show Python returning multiple values is something like this:

def foo():
   return 1, 3

a, b = foo()

But is that really returning multiple values? No. Well then how come we were able to assign to a and b? Because we got multiple values returned, right? No, this is just an application of tuple unpacking. If you're not convinced, consider than you could also do this:

c = foo()

Here, c is assigned the value (1, 3) which is a tuple. So foo() is actually returning a single value, a tuple, that contains two values that are being unpacked in the assignment. This is no different than, say

a, b = 1, 3

where, again, the value on the right hand side of the = is a 2-tuple. It would perhaps be a little more clear what is going on if the function return statement looked like

    return (1, 3)

or even 

    return [1, 3]

Effectively those two are the same as the original. One value (a sequence) is being returned which contains 2 values which are unpacked in the assignment.

So as you can see, Python can't return multiple values after all.

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