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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 vcard(self, qs):
 """VCARD format."""

        try:
            import vobject
        except ImportError:
            print(self.style.ERROR("Please install vobject to use the vcard export format."))
            sys.exit(1)

        out = sys.stdout
        for ent in qs:
            card = vobject.vCard()
            card.add('fn').value = full_name(**ent)
            if not ent['last_name'] and not ent['first_name']:
                # fallback to fullname, if both first and lastname are not declared
                card.add('n').value = vobject.vcard.Name(full_name(**ent))
            else:
                card.add('n').value = vobject.vcard.Name(ent['last_name'], ent['first_name'])
            emailpart = card.add('email')
            emailpart.value = ent['email']
            emailpart.type_param = 'INTERNET'

            out.write(card.serialize())