Added licence and copyright. Some documentation.

#!/usr/bin/env python3

# The MIT License (MIT)

# Copyright (c) 2017 Thomas Hütter, Mateusz Pawlik.

# 

# Permission is hereby granted, free of charge, to any person obtaining a copy

# of this software and associated documentation files (the "Software"), to deal

# in the Software without restriction, including without limitation the rights

# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

# copies of the Software, and to permit persons to whom the Software is

# furnished to do so, subject to the following conditions:

# 

# The above copyright notice and this permission notice shall be included in

# all copies or substantial portions of the Software.

# 

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

# SOFTWARE.

from lxml import etree

import lxml.sax

from xml.sax.handler import ContentHandler

# This class implements the sax-like events for converting XML elemnts into

# This script converts DBLP from XML to bracket notation.

# NOTE: Filenames are hardcoded in this script.

# This class implements the sax-like events for converting XML elements into

# bracket-notation nodes and labels.

class DBLPContentHandler(ContentHandler):

    def __init__(self):