arr = [1, 3, 7]
arr << 19 #arr is now [1, 3, 7, 19]
string = 'Hello'
string << ' There!' #string is now 'Hello There!'
string = 'Hello'
string << 33 #integers are added as a byte, 33 is '!' so the message is 'Hello!'
#and you can even use it with IO streams
io_stream << 'pizza!' #adds a new line to the stream, containing 'pizza!'