Def print ruler(in) This function is given a positive integer n, and prints a vertical ruler of 2! − 1 lines. Each line contains ‘-‘ marks as follows: • The line in the middle (! " ) of the ruler contains n ‘-‘ marks • The lines at the middle of each half (! # and $ # ) of the ruler contains (n-1) ‘-‘ marks • The lines at the ! % , $ % , & % and ' % of the ruler contains (n-2) ‘-‘ marks • And so on … • The lines at the ! "(, $ "(, & "(, ..., "()! "( of the ruler contains 1 ‘-‘ mark