This code calls a series of functions do draw a smiley face:
The arc() function takes 6 parameters: the first 4 parameters define an ellipse, and the last 2 parameters specify a limit (in radians) that causes the computer to only draw part of the ellipse. In radians, 0 is the right-most point of the ellipse, and pi (we’re using 3.14 which is close enough) is the left-most point of the ellipse. That lets us draw only half the ellipse for the mouth.
This is a companion discussion topic for the original entry at https://happycoding.io/examples/processing/calling-functions/smiley-face