I have a dictionary. If V is in DICT[K] then someFunc(k, v) and someFunc(v, k) both return true (and K is in DICT[V]). The dictionary could look like this:

```
{
1: [2, 3, 5],
2: [3, 1, 5],
3: [1, 2],
5: [2, 1],
}
```

I want to find all sets of numbers of a certain length inside a dictionary that fit this criteria: someFunc(x, y) and someFunc(y, x) must be true for any pair in the dictionary. For example, for the dictionary I showed:

{1, 2, 3} would be a valid length 3 set. The criteria must be valid as all items contain every other item:

- dict[1] contains 2, 3
- dict[2] contains 1, 3
- dict[3] contains 1, 2

What is the best way to find all such sets of a given length in a given dict, if I know that all valid sets must contain a given number.