def tag(self, rs_uid, dict_of_stuff, update='upsert'):
'''
Parameters
----------
rs_uid : str
the uid of the rustart to tag
dict_of_stuff : dict
extra post-collection metadata to insert into tag collection
update : {'upsert', 'replace', 'insert_only'}
What to do if this runstart already has a tag
'''
See https://github.com/NSLS-II/dataportal/issues/194
Proposal:
add a
tags
collection to mds