after this linethe execution loops back to the start of the game loop and begin the process all over again this waythe blocks are constantly moving littlebouncing off the wallsand being drawn on the screen in their new positions the call to the time sleep(function is there because the computer can movebounceand draw the blocks so fast that if the program ran at full speedall the blocks would look like blur (try commenting out the time sleep( line and running the program to see this this call to time sleep(will stop the program for secondsor milliseconds drawing trails of blocks comment out line (the windowsurface fill(blacklineby adding to the front of the line now run the program without the call to windowsurface fill(black)you don' black out the entire window before drawing the rectangles in their new position the trails of rectangles appear because the old rectangles drawn in previous iterations through the game loop aren' blacked out anymore remember that the blocks are not really moving on each iteration through the game loopthe code redraws the entire window with new blocks that are located few pixels over each time summary this has presented whole new way of creating computer programs the previous programs would stop and wait for the player to enter text howeverin our animation programthe program is constantly updating the data structures of things without waiting for input from the player remember in our hangman and tic tac toe games we had data structures that would represent the state of the boardand these data structures would be passed to drawboard(function to be displayed on the screen our animation program is similar the blocks variable holds list of data structures representing blocks to be drawn to the screenand these are drawn to the screen inside the game loop but without calls to input()how do we get input from the playerin our next we will cover how programs can know when the player presses keys on the keyboard we will also learn of concept called collision detection