linestrings to polygon

import codecs
from sys import argv

lines = codecs.open(argv[1], 'r', 'utf-8-sig').readlines()

segments = []

for line in lines:
    out = []
    for point in line.split(' '):
        if not point.strip(): continue
        out.append(map(float, point.split(',')))
    segments.append(out)

polygon = []

overlap = segments[0][0]
polygon.append(overlap)

while segments:
    for seg in segments:
        if seg[0] == overlap:
            polygon.extend(seg[1:])
            overlap = polygon[-1]
            segments.remove(seg)

print '''<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.0">
<Placemark><Polygon><outerBoundaryIs><LinearRing><coordinates>'''

for point in polygon:
    print "%s,%s,%s" % (point[0], point[1], point[2]),

print '</coordinates></LinearRing></outerBoundaryIs></Polygon></Placemark></kml>'