def polymorphic_belongs_to(*symbols, &block)
        options = symbols.extract_options!
        options.merge!(polymorphic: true)
        belongs_to(*symbols, options, &block)
      end
def polymorphic_belongs_to(*symbols, &block)
        options = symbols.extract_options!
        options.merge!(polymorphic: true)
        belongs_to(*symbols, options, &block)
      end
A quick method to declare polymorphic belongs to.