the first time the execution comes to this while statementline will have just assigned 'yesto the playagain variable that means the condition will be true this guarantees that the execution enters the loop at least once calling the functions in the program displayintro(line calls the displayintro(function this isn' python functionit is your function that you defined earlier on line when this function is calledthe program execution jumps to the first line in the displayintro(function on line when all the lines in the function are donethe execution jumps back to line and continues moving down cavenumber choosecave(line also calls function that you defined remember that the choosecave(function lets the player type in the cave they want to go into when the line ' return cave executesthe program execution jumps back to line and the choosecave(call evaluates to the return value this return value is stored in new variable named cavenumber then the program execution moves on to line checkcave(cavenumberline calls your checkcave(functionpassing the value in cavenumber as an argument not only does execution jump to line but the value in cavenumber is copied to the parameter chosencave inside the checkcave(function this is the function that will display either 'gives you his treasure!or 'gobbles you down in one bite!depending on the cave the player chose to go into asking the player to play again print('do you want to play again(yes or no)'playagain input(whether the player won or lostthey are asked if they want to play again the variable playagain stores what the player typed line is the last line of the while-blockso the program jumps back to line to check the while loop' conditionplayagain ='yesor playagain ='yif the player typed in the string 'yesor ' 'then the execution would enter the loop again at line