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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 find_all_files(self):
 		""" 		Find files including those in subrepositories. 		"""

		files = self.find_files()
		subrepo_files = (
			posixpath.join(subrepo.location, filename)
			for subrepo in self.subrepos()
			for filename in subrepo.find_files()
		)
		return itertools.chain(files, subrepo_files)