code: public static final boolean isSingletonInstantiated (@Nullable final IScope aScope,
                                                         @Nonnull final Class <? extends AbstractSingleton> aClass)
    {
      return getSingletonIfInstantiated (aScope, aClass) != null;
    }
docs: Check if a singleton is already instantiated inside a scope
  
  @param aScope
  The scope to check. May be <code>null</code> to avoid constructing a
  scope.
  @param aClass
  The class to be checked. May not be <code>null</code>.
  @return <code>true</code> if the singleton for the specified class is
  already instantiated, <code>false</code> otherwise.