sum = 1 + 1
sum.class # => Fixnum

array = [1,2,3]
array << 4
array = 5

symbol = :foo

hash = {:arg1 => "val1", :arg2 => "val2"}
hash[:arg3] = "val3"

@instance_variable = "string"

def my_method(arg1)
  puts arg1
end