```
return [[nums[offset] for offset in range(inclusions.bit_length()) if inclusions&(1<<offset) != 0] for inclusions in range(1<<len(nums))]
```

Here's the rundown:

We're trying to generate the set of all subsets (aka power set) of a list.

```
... nums[offset] for offset in range(inclusions.bit_length()) ...
```

To keep track of which elements are kept, inclusion is encoded as 1, exclusion as 0. The number of bits used is the size of the input. For 3 elements, it goes from 0 to 7 (111 in binary). For 16 elements, 0x0 to 0xFFFF.

For example, if num = [1, 2, 3]:

000 => []

100 => [1]

101 => [1, 3]

111 => [1, 2, 3]

```
... if inclusions&(1<<offset) != 0 ...
```

Bit masking checks if an element should be included or not.

```
... for inclusions in range(1<<len(nums)) ...
```

For input of size N, there will be 2^N iterations, starting at 0, ending at 2^N-1.