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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 join_domain(name,
                username=None,
                password=None,
                account_ou=None,
                account_exists=False,
                restart=False):
    '''
    Checks if a computer is joined to the Domain. If the computer is not in the
    Domain, it will be joined.

    Args:

        name (str):
            The name of the Domain.

        username (str):
            Username of an account which is authorized to join computers to the
            specified domain. Need to be either fully qualified like
            user@domain.tld or simply user.

        password (str):
            Password of the account to add the computer to the Domain.

        account_ou (str):
            The DN of the OU below which the account for this computer should be
            created when joining the domain,
            e.g. ou=computers,ou=departm_432,dc=my-company,dc=com.

        account_exists (bool):
            Needs to be set to ``True`` to allow re-using an existing computer
            account.

        restart (bool):
            Needs to be set to ``True`` to restart the computer after a
            successful join.

    Example:

    .. code-block:: yaml

        join_to_domain:
          system.join_domain:
            - name: mydomain.local.com
            - username: myaccount@mydomain.local.com
            - password: mysecretpassword
            - restart: True
    '''

    ret = {'name': name,
           'changes': {},
           'result': True,
           'comment': 'Computer already added to \'{0}\''.format(name)}

    current_domain_dic = __salt__['system.get_domain_workgroup']()
    if 'Domain' in current_domain_dic:
        current_domain = current_domain_dic['Domain']
    elif 'Workgroup' in current_domain_dic:
        current_domain = 'Workgroup'
    else:
        current_domain = None

    if name.lower() == current_domain.lower():
        ret['comment'] = 'Computer already added to \'{0}\''.format(name)
        return ret

    if __opts__['test']:
        ret['result'] = None
        ret['comment'] = 'Computer will be added to \'{0}\''.format(name)
        return ret

    result = __salt__['system.join_domain'](domain=name,
                                            username=username,
                                            password=password,
                                            account_ou=account_ou,
                                            account_exists=account_exists,
                                            restart=restart)
    if result is not False:
        ret['comment'] = 'Computer added to \'{0}\''.format(name)
        if restart:
            ret['comment'] += '\nSystem will restart'
        else:
            ret['comment'] += '\nSystem needs to be restarted'
        ret['changes'] = {'old': current_domain,
                          'new': name}
    else:
        ret['comment'] = 'Computer failed to join \'{0}\''.format(name)
        ret['result'] = False
    return ret