def NOT(condition)
      unless conditionable? condition
        raise TypeError, 'wrong object for condition'
      end

      ->v{! _valid?(condition, v)}
    end
def NOT(condition)
      unless conditionable? condition
        raise TypeError, 'wrong object for condition'
      end

      ->v{! _valid?(condition, v)}
    end
A condition builder.
 @param condition [Proc, Method, #===]
 @return [lambda] A condition invert the original condition.