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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def is_file(cls, file):
        '''Return whether the file is likely to be HTML.'''
        peeked_data = wpull.string.printable_bytes(
            wpull.util.peek_file(file)).lower()

        if b'<!doctype html' in peeked_data \
           or b'<head' in peeked_data \
           or b'<title' in peeked_data \
           or b'<html' in peeked_data \
           or b'<script' in peeked_data \
           or b'<table' in peeked_data \
           or b'<a href' in peeked_data:
            return True