Lab 1. How many schools in Massachusetts?

Let’s stream-process the 3GB Open Street Map (OSM) XML file 
for the state of Massachusetts.

See massachusetts.xml in this folder: huge-file

Here is a snippet of the XML file; it shows the data for one 
of the schools in Massachusetts:

<osm version="0.6" generator="osm-extract.pl">
    ...
    <node id="358264143" version="1" timestamp="2009-03-10T04:54:34Z"
          uid="4732" user="iandees" changeset="774950" lat="42.2017681"
          lon="-70.7561527">
        <tag k="gnis:created" v="08/27/2002"/>
        <tag k="gnis:county_id" v="023"/>
        <tag k="name" v="Scituate Center Central School"/>
        <tag k="amenity" v="school"/>
        <tag k="gnis:feature_id" v="602607"/>
        <tag k="gnis:state_id" v="25"/>
        <tag k="ele" v="34"/>
    </node>
    ...
</osm>

A <node> represents a school if it has a <tag> with @k="amenity" @v="school".

You are to write an XSLT program which stream-processes massachusetts.xml and
outputs a count of the number of schools in Massachusetts.