#! /usr/bin/env python2.7
# -*- mode: python tab-width: 4 coding: utf-8 -*-
#
import re

text = """# excluded.txt
#
# $Revision: $
# $Date: 2015-04-27 19:52:22 +0100 (Mon, 27 Apr 2015) $
#
# leading and trailing whitespace is ignored
# comments start with a hash
# other lines contain space separated NGRs either myriads, hectads or tetrads
# myriads are two characters e.g. TQ
#
HL HM HN HO   JL JM JN  # myriads
HQ HR HS      JQ JR JS
"""

# simple regular expression to remove the '#' comments
# from the above text

## these work
# data = re.sub(r'(?m)#.*', '', text)
# data = re.sub(r'#.*', '', text, re.MULTILINE|re.DEBUG)

## but this fails
data = re.sub(r'#.*', '', text, re.MULTILINE)

lines = data.splitlines()
for line in lines:
    print(line)