def list_holds(service, matter_id):
    """
     Return a list of existing holds
    """
    done_paginating = False
    response = service.matters().holds().list(matterId=matter_id).execute()
    # append first page:
    the_holds = response['holds']
    # Keep paginating and appending:
    while not done_paginating:
        if 'nextPageToken' in response:
            response = service.matters().holds.list(pageSize=10, pageToken=response['nextPageToken']).execute()
            the_holds.extend(response['holds'])
        else:
            done_paginating = True
    return the_holds