This example is explained to draw a rectangle, however in the code it uses the line f(x) when it should use the rect() function. It's the same issue with the noStroke, height, width examples.
In the TFTPoint example, it should use the stroke(X,X,X) instead of fill(X,X,X)
Colors chosen in the Draw Circle example could have been more contrast with each. Gray and White blend too close. The radius of circle could have been made a little bigger for better demonstrating.