help page shows unwanted information about groups

I have a file called `neptune` that just has some standalone functions, no classes or groups.

I create my cli by doing
```
if __name__ == '__main__':
fire.Fire()
```

When I do `neptune --help`, I see


I don't understand why it says

f - "Character and line based layer over a BufferedIOBase object, buffer"

I don't want to see that information about the `f` group when I do `neptune --help`

A workaround I came up with was to do this instead
```
if __name__ == '__main__':
fire.Fire({
'cmd1': cmd1,
'cmd2': cmd2,
...
})
```
This doesn't seem intuitive.

I'd be happy to help fix this if someone wants to point me in the right direction!

Start by reproducing the issue with a standalone `neptune` file and the `fire.Fire()` entry point, then compare its `--help` output with the explicit command mapping workaround. The fix is done when standalone functions no longer cause an unrelated `f` group and its BufferedIOBase description to appear in help.

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