def value
      # Model must be solved to have a value
      return nil unless @model && @model.status == :optimized

      value = @model.variable_value self

      case @type
      when :integer
        value.round
      when :binary
        [false, true][value.round]
      else
        value
      end
    end
def value
      # Model must be solved to have a value
      return nil unless @model && @model.status == :optimized

      value = @model.variable_value self

      case @type
      when :integer
        value.round
      when :binary
        [false, true][value.round]
      else
        value
      end
    end
Get the final value of this variable