unless considered harmful

a.rb

class Muto
    def initialize(sniper)
        @sniper = sniper
    end

    def with_sniper?
        @sniper
    end

    def without_sniper?
        !@sniper
    end
end

mu10 = Muto.new(true)

# no
if !mu10.with_sniper?
    puts 'yes'
else
    puts 'no'
end

# yes
unless mu10.without_sniper?
    puts 'yes'
else
    puts 'no'
end