def base?
      return @base if defined? @base
      @base = (@numerator + @denominator)
              .compact
              .uniq
              .map { |unit| RubyUnits::Unit.definition(unit) }
              .all? { |element| element.unity? || element.base? }
      @base
    end
def base?
      return @base if defined? @base
      @base = (@numerator + @denominator)
              .compact
              .uniq
              .map { |unit| RubyUnits::Unit.definition(unit) }
              .all? { |element| element.unity? || element.base? }
      @base
    end
Is this unit in base form?
 @return [Boolean]