class_docstr: A counter to count ratio of something. 
code: def ratio(self):
      if self._tot == 0:
          return 0
      return self._cnt * 1.0 / self._tot
  
imports: import numpy
label_desc: Use image node_id 4 for calling the RatioCounter obj's underlying member method code with example usage: obj.ratio() and returns: unknown, int