In the user guide, the role execution command is not clear

For example:

the master account execute:
GRANT USER ln_write_user PRIVILEGES 'INSERT_TIMESERIES' on root.ln
Msg: The statement is executed successfully.
IoTDB> GRANT USER sgcc_write_user PRIVILEGES 'INSERT_TIMESERIES' on root.sgcc
Msg: The statement is executed successfully.
IoTDB> exit

Sub account execute:

premise: login successfully
execute:

IoTDB> login successfully
IoTDB> INSERT INTO root.ln.wf01.wt01(timestamp, status) values(1509465600000, true)
Msg: The statement is executed successfully.

location:Administration Management/Grant User Privilege