code: def get_roles_request(request):
      
      uuid_ = request.matchdict['uuid']
      user_id = request.matchdict.get('uid')
  
      args = [uuid_]
      if user_id is not None:
          fmt_conditional = "AND user_id = %s"
          args.append(user_id)
      else:
          fmt_conditional = ""
  
      with db_connect() as db_conn:
          with db_conn.cursor() as cursor:
              cursor.execute("""\
  SELECT row_to_json(combined_rows) FROM (
  SELECT uuid, user_id AS uid, role_type AS role, accepted AS has_accepted
  FROM role_acceptances AS la
  WHERE uuid = %s {}
  ORDER BY user_id ASC, role_type ASC
  ) as combined_rows""".format(fmt_conditional), args)
              acceptances = [r[0] for r in cursor.fetchall()]
  
              if not acceptances:
                  if user_id is not None:
                      raise httpexceptions.HTTPNotFound()
                  else:
                      cursor.execute("""\
  SELECT TRUE FROM document_controls WHERE uuid = %s""", (uuid_,))
                      try:
                          cursor.fetchone()[0]
                      except TypeError:  # NoneType
                          raise httpexceptions.HTTPNotFound()
  
      resp_value = acceptances
      if user_id is not None:
          resp_value = acceptances[0]
      return resp_value
docs: Returns a list of accepting roles.