The Python code creates a Tkinter window that contains a Canvas object called
the_canvas. We use the bind function here, which will bind a specific event that occurs on this widget (the_canvas) to a specific action or key press. In this case, we bind the <Motion> function of the mouse, plus the click and release of the first mouse button (<ButtonPress-1> and <ButtonRelease-1>). Each of these events are then used to call the mouse1press(), mouse1release(), and mousemove() functions.

The logic here is to track the status of the mouse button using the mouse1press() and mouse1release() functions.

If the mouse button has been clicked, the mousemove() function will check to see whether we are drawing a new line (we set new coordinates for this) or continuing an old one (we draw a line from the previous coordinates to the coordinates of the current event that has triggered mousemove()). We just need to ensure that we reset to the newline command whenever the mouse button is released to reset the start position of the line.