Co-authored-by: sunfish <[email protected]>

Previously the documentation mistakenly stated the argument `h` was used for getting the `diagnostic_period` parameter. I fixed the documentation.

The data returned from a socket is `bytes`. So to properly deal with
this data we'd have to concatenate as bytes and decode to string at the
end.

The old (wrong) way of concatenating results in some stray `'b'`
characters showing up in the drive names.

…noetic-devel