It uses standard search query syntax.
It returns grouped objects and their count from highest occurrence to lowest
fcpc groupby name query
fcpc groupby tag +
fcpc groupby tag link+
For example, to filter only tags with root sys:
fcpc groupby tag[sys:] +
usage: fcpc groupby [-h] attrs [query ...]
positional arguments:
attrs Attribute[s] to group on. Use comma for more attributes
query
optional arguments:
-h, --help show this help message and exit