MAKE "SINGLE.STEP "TRUE
SINGLE.STEP is a pre-defined name that allows monitoring of procedure or command line execution. SINGLE.STEP displays each step of a line or procedure before execution and pauses until you type CONTINUE or CO.
SINGLE.STEP allows the user to test the expression with different variables or perform other computations during the pause.
To return to toplevel before the entire procedure has run, type Control-G or TOPLEVEL during the pause.
To turn off SINGLE.STEP, type:
MAKE "SINGLE.STEP "FALSE