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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 _inherited_dashboard(dashboard, base_dashboards_from_pillar, ret):
    '''Return a dashboard with properties from parents.'''
    base_dashboards = []
    for base_dashboard_from_pillar in base_dashboards_from_pillar:
        base_dashboard = __salt__['pillar.get'](base_dashboard_from_pillar)
        if base_dashboard:
            base_dashboards.append(base_dashboard)
        elif base_dashboard_from_pillar != _DEFAULT_DASHBOARD_PILLAR:
            ret.setdefault('warnings', [])
            warning_message = 'Cannot find dashboard pillar "{0}".'.format(
                base_dashboard_from_pillar)
            if warning_message not in ret['warnings']:
                ret['warnings'].append(warning_message)
    base_dashboards.append(dashboard)

    result_dashboard = {}
    tags = set()
    for dashboard in base_dashboards:
        tags.update(dashboard.get('tags', []))
        result_dashboard.update(dashboard)
    result_dashboard['tags'] = list(tags)
    return result_dashboard