code: def decrease_refcount(self, op):
      op.refcount -= 1
      if op.refcount == 0:
          del self.op_dict[op.node.name]
          return True
      return False
  
imports: import numpy
  import tensorflow.compat.v1
  from tensorflow.core.framework.tensor_pb2 import TensorProto
  from tensorflow.core.framework.tensor_shape_pb2 import TensorShapeProto
label_desc: Use image node_id 20 for calling the RefineGraph obj's underlying member method code with example usage: obj.decrease_refcount(op) and returns: False, True