The most obvious feature of Forth is the stack. When you type in a
number, it is pushed on the stack. You can display the contents of the
stack with .s.
1 2 .s 3 .s
.s displays the top-of-stack to the right, i.e., the numbers
appear in .s output as they appeared in the input.
You can print the top element of the stack with ..
1 2 3 . . .
In general, words consume their stack arguments (.s is an
exception).
Assignment: What does the stack contain after
5 6 7 .?