- Global : $var
- Class : @@var
- Instance : @var
- Local : var
- Block : var
obj.class
"1".class
nombre = "Juan"
puts "Hola #{nombre}"
puts "1+1=#{1+1}"
x.nil?
[].empty?
[1].include?(1)
2.between?(3,4)
{"a" => "ax2"}.has_key?("a")
{"a" => "ax2"}.has_value?("ax2")