[Python] How does this function to search nodes in an XML tree work?

I can't understand what this lookup function is doing:

def lookup(d, key):
found = False
for child in d:
if found : return child.text
if child.tag == 'key' and child.text == key :
found = True
return None


This is the full piece of code, also if you need to find the Library.xml file, you can go to this link to see for more context: https://www.py4e.com/code3.zip to download the zip file and then you can go to the tracks file to find the library.xml file.

import xml.etree.ElementTree as ET
import sqlite3

conn = sqlite3.connect('trackdb.sqlite')
cur = conn.cursor()

# Make some fresh tables using executescript()
cur.executescript('''
DROP TABLE IF EXISTS Artist;
DROP TABLE IF EXISTS Album;
DROP TABLE IF EXISTS Track;

CREATE TABLE Artist (
id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,
name TEXT UNIQUE
);

CREATE TABLE Album (
id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,
artist_id INTEGER,
title TEXT UNIQUE
);

CREATE TABLE Track (
id INTEGER NOT NULL PRIMARY KEY
AUTOINCREMENT UNIQUE,
title TEXT UNIQUE,
album_id INTEGER,
len INTEGER, rating INTEGER, count INTEGER
);
''')


fname = input('Enter file name: ')
if ( len(fname) < 1 ) : fname = 'Library.xml'

# <key>Track ID</key><integer>369</integer>
# <key>Name</key><string>Another One Bites The Dust</string>
# <key>Artist</key><string>Queen</string>
def lookup(d, key):
found = False
for child in d:
if found : return child.text
if child.tag == 'key' and child.text == key :
found = True
return None

stuff = ET.parse(fname)
all = stuff.findall('dict/dict/dict')
print('Dict count:', len(all))
for entry in all:
if ( lookup(entry, 'Track ID') is None ) : continue

name = lookup(entry, 'Name')
artist = lookup(entry, 'Artist')
album = lookup(entry, 'Album')
count = lookup(entry, 'Play Count')
rating = lookup(entry, 'Rating')
length = lookup(entry, 'Total Time')

if name is None or artist is None or album is None :
continue

print(name, artist, album, count, rating, length)

cur.execute('''INSERT OR IGNORE INTO Artist (name)
VALUES ( ? )''', ( artist, ) )
cur.execute('SELECT id FROM Artist WHERE name = ? ', (artist, ))
artist_id = cur.fetchone()[0]

cur.execute('''INSERT OR IGNORE INTO Album (title, artist_id)
VALUES ( ?, ? )''', ( album, artist_id ) )
cur.execute('SELECT id FROM Album WHERE title = ? ', (album, ))
album_id = cur.fetchone()[0]

cur.execute('''INSERT OR REPLACE INTO Track
(title, album_id, len, rating, count)
VALUES ( ?, ?, ?, ?, ? )''',
( name, album_id, length, rating, count ) )

conn.commit()

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