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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 var_unset(session, name):
 """ Unsets the given variable """

        name = name.strip()
        try:
            session.unset(name)
        except KeyError:
            session.write_line("Unknown variable: {0}", name)
            return False
        else:
            session.write_line("Variable {0} unset.", name)

        return None