@active(string)
@active(proc)
@active(exe)
@active()
returns in a tab the active (alive) exe of the instances of a
process or an object specified through its name (a string with or
without the prefix :: or obj::) or through its proc value. If the
argument is an exe, it returns the empty tab if the exe is dead and a
singleton (with the argument) if it is alive. With no argument, it returns
all active exe in a tab.
See also @number_active