Note that USER_LOCK package is not part of the default Oracle installation.
Follow this link to install it before running the demo: USER_LOCK Info and Installation.
Arguments
set linesize 121
col package_name format a20
col argument_name format a17
col data_type format a14
col pls_type format a14
SELECT package_name, argument_name, data_type, data_length,
data_precision, pls_type FROM all_arguments WHERE object_name = 'SLEEP' ORDER BY 1;