class_docstr: Reader that reads from an upstream reader, calls the processor, and returns
  the processed record.
class_docstr_tok: ["Reader","that","reads","from","an","upstream","reader",",","calls","the","processor",",","and","returns","the","processed","record","."]
code: def read_ex(self, init_net, exit_net):
      read_nets, status, rec = self.reader.read_record_ex(
          init_net, exit_net
      )
      # We don't use status as stop_blob of NetBuilder it's not guarantee that
      # it would end up being the true stob_blob. For example,
      # ReaderWithLimitBase doesn't pass the status through but rather copy
      # from it.
      with NetBuilder() as nb:
          # Current NetBuilder is optionally used inside the processor,
          # then its children are retrieved inside of
          # normalize_processor_output.
          # Once readers and writers also use NetBuilder,
          # this logic will be more natural.
          result = normalize_processor_output(self.processor(rec))
      read_nets += result.nets
      if result.should_stop or nb._stop_blob:
          stop_net = core.Net("stop_net")
          if result.should_stop:
              stop_net.Or([status, result.should_stop], [status])
          if nb._stop_blob:
              stop_net.Or([status, nb._stop_blob], [status])
          read_nets.append(stop_net)
      if hasattr(self.processor, "setup"):
          init_net.add_attribute(TaskGroup.LOCAL_SETUP, self.processor)
      self._set_schema(result.record)
      fields = result.record.field_blobs() if result.record else None
      return read_nets, status, fields
  
imports: from caffe2.python import core, queue_util
  from caffe2.python.dataio import Reader, Writer
  from caffe2.python.net_builder import NetBuilder, ops
  from caffe2.python.schema import as_record, Field
  from caffe2.python.task import Node, Task, TaskGroup
label_desc: Use image node_id 4 for calling the ProcessingReader obj's underlying member method code with example usage: obj.read_ex(init_net, exit_net) and returns: read_nets,  status,  fields