code: def server_mode_cluster_role_env(cluster_role_env, config_map):
    
  
    cmap = config_map[cluster_role_env[0]]
  
    # if role is required but not provided, raise exception
    role_present = True if len(cluster_role_env[1]) > 0 else False
    if ROLE_KEY in cmap and cmap[ROLE_KEY] and not role_present:
      raise Exception("role required but not provided (cluster/role/env = %s)."\
          % (cluster_role_env))
  
    # if environ is required but not provided, raise exception
    environ_present = True if len(cluster_role_env[2]) > 0 else False
    if ENVIRON_KEY in cmap and cmap[ENVIRON_KEY] and not environ_present:
      raise Exception("environ required but not provided (cluster/role/env = %s)."\
          % (cluster_role_env))
  
    return True
docs: Check cluster/[role]/[environ], if they are required