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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 get_file(self, filename, dir='static'):
 """ get_file will search from apps directory """

        if os.path.exists(filename):
            return filename
        dirs = self.apps
        if dir:
            fname = os.path.join(dir, filename)
        else:
            fname = filename
        for d in reversed(dirs):
            path = pkg.resource_filename(d, fname)
            if os.path.exists(path):
                return path
        return None