for i in range(n_feats):
    feat = layer.GetFeature(i)
    # get start and end points of feature
    # get bounding box of feature

    layer.SetSpatialFilterRect(bbox[0], bbox[3], bbox[2], bbox[1])
    n_feats_select = layer.GetFeatureCount()
    for dummy_i in range(n_feats_select):
        feat_select = layer.GetNextFeature()
        # check if feature intersects with previously gotten start and end points
        # if they don't, feature has a dangle, do stuff

    layer.SetSpatialFilter(None)