task
Essentially, count the number of occurrences of =={{header| on each task page.

Output:

100 doors: 20 examples.
99 Bottles of Beer: 29 examples.
Abstract type: 10 examples.

Total: X examples.
For a full output, updated periodically, see Rosetta Code/Count examples/Full list.

You'll need to use the Media Wiki API, which you can find out about locally, here, or in Media Wiki's API documentation at, API:Query

from urllib.request import urlopen, Request
import xml.dom.minidom
 
r = Request(
 'https://www.rosettacode.org/mw/api.php?action=query&list=categorymembers&cmtitle=Category:Programming_Tasks&cmlimit=500&format=xml',
 headers={'User-Agent': 'Mozilla/5.0'})
x = urlopen(r)
 
tasks = []
for i in xml.dom.minidom.parseString(x.read()).getElementsByTagName('cm'):
    t = i.getAttribute('title').replace(' ', '_')
    r = Request(f'https://www.rosettacode.org/mw/index.php?title={t}&action=raw',
         headers={'User-Agent': 'Mozilla/5.0'})
    y = urlopen(r)
    tasks.append( y.read().lower().count(b'{{header|') )
    print(t.replace('_', ' ') + f': {tasks[-1]} examples.')
 
print(f'\nTotal: {sum(tasks)} examples.')
 