module ActiveSupport::Dependencies::Loadable

+false+ otherwise.
Returns +true+ if the constant was not previously marked for unloading,

or a qualified constant name as a string or symbol.
The provided constant descriptor may be a (non-anonymous) module or class,

for the first clear.
each constant will be removed for every subsequent clear, as opposed to
or init scripts may list each unloadable constant that may need unloading;
Note that marking a constant for unloading need only be done once. Setup

each time dependencies are cleared.
Mark the given constant as unloadable. Unloadable constants are removed

def unloadable(const_desc)
  Dependencies.mark_for_unload const_desc
end