in PYTHON please

Implement a class named HeadingParser that can be used to parse an HTML document, and retrieve and print all the headings in the document. You should implement your class as a subclass of HTMLParser, defined in Standard Library module html.parser. When fed a string containing HTML code, your class should print the headings, one per line and in the order in which they appear in the document. Test your implementation using the file w3c.html provided. >>> in file = - open('w3c.html) >>> content = infile.read() >>> infile.close() >>> hp = HeadingParser() >>> hp.feed(content) W3C Mission Principles