Without a parameter, this command displays a dialog box letting the user select and execute one of the last executed repeatable commands.
index_in_command_history specifies which command found in the command history is to be executed. Note that index 0 specifies the most recently executed command in the command history. When this index is specified, the selector dialog box is not displayed and specified command is automatically executed (when this is allowed given current editing context).
repeat, this command returns the result of repeated command (if any).