def _get_fillcolor(resource_type, properties, known_sg=[], open_sg=[]):
    """Determine fillcolor for resources (public ones in this case)
    """
    fillcolor = None
    if 'SecurityGroups' in properties:
        for sg in properties['SecurityGroups']:
            if 'Ref' in sg and sg['Ref'] not in known_sg:
                fillcolor = 'yellow'
                break
        for osg in open_sg:
            if {'Ref': osg} in properties['SecurityGroups']:
                fillcolor = 'red'
                break
    if resource_type == 'LoadBalancer':
        if 'Scheme' not in properties or properties['Scheme'
            ] == 'internet-facing':
            fillcolor = 'red'
    return fillcolor
