auto_load ?command?
Attempt to load the specified command from a loadable library.
loading the package containing the procedure. If the package
indexes have not been loaded for all package libraries in
auto_path, they will be loaded. Out-of-date library indexes will
be rebuilt if they are writable. The procedure returns 1 if the
command was successfully loaded, or 0 if it was not.
Duplicated package names are skipped, the first package of a
given name found in the path is loaded. If the auto_path has
changed since the last load, indexes will be reloaded (duplicate
packages will not be redefined).
If command is not specified, the indexes will be loaded, if they
have not already been loaded or if the auto_path variable has
changed, but no command will be loaded.
This command overrides the standard Tcl procedure of the
same name.
This command is provided by Extended Tcl.