Return doesn't work (python)

I've been having some problems with the return statement and I can't seem to figure out what's wrong. It seemed to work fine yesterday, but today no function that contains it seems to work properly. Here's an example of what's going on:

def fpol(x):
    y=x**4
    return(y)

If I then type in

fpol(4)

I'm given the answer 256 (as I would expect). If I then type in

print(y)

or try to use/view y in any way, I'm told

NameError: name 'y' is not defined

I've also tried it with return(y) being replaced by return y . I can also insert print(y) into the original function and that works fine, so I know that during the function, y actually does have a value, it's just not being returned. Any help is much appreciated.

Edit: I've now been able to work past the issue I had with the return function. Thanks to everyone who responded.

Solution

I suspect you are trying to print(y) outside the function. The variable y is local in scope, that is only defined within fpol(). So you can print it there. You can do:,

def fpol(x):
    y=x**4
    return(y)

y = fpol(4)
print(y)

But not:

def fpol(x):
    y=x**4
    return(y)

print(y)