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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 iterfiles(self, pattern=None, abspath=False):
 """ Generator for all the files not excluded recursively. Return relative path. :type pattern: str :param pattern: Unix style (glob like/gitignore like) pattern """

        if pattern is not None:
            globster = Globster([pattern])
        for root, dirs, files in self.walk():
            for f in files:
                if pattern is None or (pattern is not None and globster.match(f)):
                    if abspath:
                        yield os.path.join(root, f)
                    else:
                        yield self.relpath(os.path.join(root, f))