code: def count_matches(self, matches):
      num_matches = 0
      for batch in range(self.be.bsz):
          inds = matches[batch]["inds"]
          num_matches += len(np.where(inds > -1)[0])
  
      return num_matches
  
imports: from neon import NervanaObject
  import numpy
  from util import util
  from neon.transforms import Softmax
label_desc: Use image node_id 8 for calling the MBoxLoss obj's underlying member method code with example usage: obj.count_matches(matches) and returns: num_matches