update May  30, 2013
NAME
ruler.py - Print a text ruler for use in numbering columns
SYNOPSIS
ruler
DESCRIPTION

This is a very simple script that prints out two lines of text that can be pasted into any text document, usually in a text editor. The ruler is an easy trick for finding out which columns parts of data may be in. The output looks like this:

         1         2         3         4         5         6         7         8
12345678901234567890123456789012345678901234567890123456789012345678901234567890

       Note that ruler output is only useful with fixed fonts such as Courier.


EXAMPLE
Suppose you were writing a script to parse a GenBank file. The location of data in GenBank files occupies specific columns. By pasting the output of ruler to any location in a GenBank file,
you can easily see which columns are included in a field. For example, the locus name begins in column 13, and the topology field begins in column 56.
         1         2         3         4         5         6         7         8
12345678901234567890123456789012345678901234567890123456789012345678901234567890
LOCUS       PEADRRB                  594 bp    mRNA    linear   PLN 27-APR-1993
DEFINITION  Pea (P.sativum) disease resistance response protein (PI206) mRNA,
            3. end.
ACCESSION   M18250

AUTHOR
Dr. Brian Fristensky
Department of Plant Science
University of Manitoba
Winnipeg, MB  Canada R3T 2N2
frist@cc.umanitoba.ca
http://home.cc.umanitoba.ca/~frist