p5.js noErase() Function

function setup() {
    createCanvas(600, 400);
    textSize(20);
    firstBlockSlider = createSlider(50, 250, 75, 1);
    firstBlockSlider.position(30, 50);
 
    secondBlockSlider = createSlider(50, 250, 175, 1);
    secondBlockSlider.position(30, 120);
}
 
function draw() {
    clear();
    fill('black');
    text("Move the slider below to change the"
        + " first block's position", 20, 30);
    text("Move the slider below to change the"
        + " second block's position", 20, 100);
    text("The black circle demonstrates the"
        + " erase area", 20, 170);
 
    fill('red');
    rect(firstBlockSlider.value(), 200, 50, 100);
 
    // Start erasing with erase()
    erase();
    circle(150, 250, 100);
 
    // Stop erasing with noErase()
    noErase();
 
    fill('red');
    rect(secondBlockSlider.value(), 200, 50, 100);
 
    // Circle to illustrate the erase position
    noFill();
    circle(150, 250, 100);
}