def get_users(client):
    """Return the db containing users metadata.
    
    Parameters
    ----------
    client --> pymongo.mongo_client.MongoClient class, MongoDB client
    
    Returns
    -------
    metadatafs['fs'] --> pymongo.collection.Collection, reference to collection users
    """
    #get the MongoDb collection called "users"
    metadatafs = client['metadatafs']
    return metadatafs['users']