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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 email_addresses2marc(self, key, value):
 """Populate the 595 MARCXML field. Also populates the 371 field as a side effect. """

    m_or_o = 'm' if value.get('current') else 'o'
    element = {
        m_or_o: value.get('value')
    }

    if value.get('hidden'):
        return element
    else:
        self.setdefault('371', []).append(element)
        return None