module Polyfill
  module V2_4
    module Integer
      module Round
        module Method
          def round(ndigits = 0, half: nil)
            unless [nil, :down, :even, :up, 'down', 'even', 'up'].include?(half)
              raise ArgumentError, "invalid rounding mode: #{half}"
            end
            ndigits = ndigits.to_int
            return super() if ndigits == 0
            return to_f if ndigits > 0

            place = 10 ** -ndigits
            (self.to_f / place).round * place
          end if RUBY_VERSION < '2.4.0'
        end

        if RUBY_VERSION < '2.4.0'
          refine ::Integer do
            include Method
          end
        end
      end
    end
  end
end