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  Out-of-date library indexes will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 sucessfully 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 alreay 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.