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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 add_extension(self, extension):
 """ Adds the path to the extension to a list that will be used to extract it to the ChromeDriver :Args: - extension: path to the \\*.crx file """

        if extension:
            extension_to_add = os.path.abspath(os.path.expanduser(extension))
            if os.path.exists(extension_to_add):
                self._extension_files.append(extension_to_add)
            else:
                raise IOError("Path to the extension doesn't exist")
        else:
            raise ValueError("argument can not be null")