Woops, looks like my comment got messed up when it was rendered. Here's what I meant to say:

```fname``` is a bit confusing because this is expected to be an open file, not a filename. We typically name variables ```<something>_f``` if it is a file handle, and ```<something>_fp``` if it is a filepath (i.e. string). I recommend updating the name here to be something like ```biom_f``` to indicate that this is an open file handle to a BIOM file.