Example OW.RECF.4 :  $f_n: R \rightarrow R$ .
$f_0(x)= 1$ and $f_{n+1}(x)= 1 + x* f_n(x)$ for all $n \ge 0$.
Draw a mapping diagram and graph of $f_6(x)$ yourself, or consider the GeoGebra figures and table below.

Martin Flashman, Dec. 26, 2013, Created with GeoGebra

Notice how the points on the graph are paired with the points on the mapping diagram.
Given a point / number, $x$, on the source line, there is a unique arrow  meeting the target line at the point / number, $f_6(x)$. which corresponds to the function's value for $x$.
Check the box to see more points and arrows that correspond to the data in the spreadsheet.
Click on the point marked $x$ in the mapping diagram and use the up and down cursor controls on the keyboard to change the value of $x$ by $.25$.