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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 reverse_lookup(mnemonic: str):
 """ Find instruction that matches the mnemonic. :param mnemonic: Mnemonic to match :return: :class:`Instruction` that matches or None """

    for i in get_insns():
        if "_mnemonic" in i.__dict__ and i._mnemonic == mnemonic:
            return i

    return None