R subplot() with multiple lines

I have recently used the subplot() function of the TeachingDemos library for R: I wanted to create a simple embedded chart with multiple lines on it. The trick was to create a simple function that prepares the whole plot and pass it to the subplot() function to execute as shown below:

 > x <- function() { plot(1:3); lines(3:1) }
 > x()
 > plot(1:10)
 > subplot(x(), 5, 5)