@a = 1

def a_ditambah(b)
  @a + b
end

def tambah_a
  @a = @a + 1
end

@b = a_ditambah(2) # @b = 3
@c = a_ditambah(2) # @c = 3
tambah_a           # @a = 2
@d = a_ditambah(2) # @d = 4