docstr: Remove all boxes with any side smaller than min_size 
docstr_tok: ["Remove","all","boxes","with","any","side","smaller","than","min_size"]
code: def _filter_boxes(boxes, min_size):
      """Remove all boxes with any side smaller than min_size"""
      ws = boxes[:, 2] - boxes[:, 0] + 1
      hs = boxes[:, 3] - boxes[:, 1] + 1
      keep = np.where((ws >= min_size) & (hs >= min_size))[0]
      return keep
  
imports: from __future__ import print_function
  import sys
  import os
  import datetime
  import time
  import numpy
  import mxnet
  from mxnet import ndarray
  import cv2
  from rcnn.logger import logger
  from rcnn.processing.bbox_transform import clip_boxes
  from rcnn.processing.generate_anchor import generate_anchors_fpn, anchors_plane
  from rcnn.processing.nms import gpu_nms_wrapper, cpu_nms_wrapper
  from rcnn.processing.bbox_transform import bbox_overlaps
label_desc: Use image node_id 6 for calling the RetinaFace obj's underlying member method code with example usage: obj._filter_boxes(boxes, min_size) and returns: keep