def can_hold?(storable)
      can_hold_child?(storable) or subcontainers.detect { |ctr| ctr.can_hold?(storable) }
    end
def can_hold?(storable)
      can_hold_child?(storable) or subcontainers.detect { |ctr| ctr.can_hold?(storable) }
    end
@return [Boolean] true if this Container or a subcontainer in the hierarchy can hold the given storable

 @see #can_hold_child?