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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 create(cls, fqdn, duration, owner, admin, tech, bill, nameserver, extra_parameter, background):
 """Create a domain."""

        fqdn = fqdn.lower()
        if not background and not cls.intty():
            background = True

        result = cls.call('domain.available', [fqdn])
        while result[fqdn] == 'pending':
            time.sleep(1)
            result = cls.call('domain.available', [fqdn])

        if result[fqdn] == 'unavailable':
            raise DomainNotAvailable('%s is not available' % fqdn)

        # retrieve handle of user and save it to configuration
        user_handle = cls.call('contact.info')['handle']
        cls.configure(True, 'api.handle', user_handle)

        owner_ = owner or user_handle
        admin_ = admin or user_handle
        tech_ = tech or user_handle
        bill_ = bill or user_handle

        domain_params = {
            'duration': duration,
            'owner': owner_,
            'admin': admin_,
            'tech': tech_,
            'bill': bill_,
        }

        if nameserver:
            domain_params['nameservers'] = nameserver

        if extra_parameter:
            domain_params['extra'] = {}
            for extra in extra_parameter:
                domain_params['extra'][extra[0]] = extra[1]

        result = cls.call('domain.create', fqdn, domain_params)
        if background:
            return result

        # interactive mode, run a progress bar
        cls.echo('Creating your domain.')
        cls.display_progress(result)
        cls.echo('Your domain %s has been created.' % fqdn)