model = tf.keras.models.Model()
function = _saving_utils.trace_model_call(model)
concrete_func = function.get_concrete_function()
frozen_func = convert_variables_to_constants_v2(
concrete_func, lower_control_flow=False)
input_shape = {"input_1" : [1,640,640,3]}
_set_tensor_shapes(frozen_func.inputs, input_shape)
frozen_func.graph.as_graph_def()
tf.io.write_graph(graph_or_graph_def=frozen_func.graph,
logdir="./frozen_models",
name="model.pb",
as_text=False)