# infinite if inside a loop

I want to define a function that checks if a member of a set is another then print "well".

Let me explain it it the following example:

Assume that `Z = Compositions(17, min_part=4).list()`

, `L`

is some set and `f`

is some function.

How I can write a function such that if `f(a)`

, where `a`

is a member of `Z`

, was in `L`

, then that is "well"?

My attempt:

```
for i in in srange(len(Z)):
for j in srange(i):
if f(Z[i][j]) in L:
```

I don't know how to finish it because I just know finite `if, else`

, not more.

Can you make your example a little more concrete by providing an actual

`L`

and`f`

?