Training host call. Creates scalar summaries for training metrics. This function is executed on the CPU and should not directly reference any Tensors in the rest of the `model_fn`. To pass Tensors from the model to the `metric_fn`, provide as part of the `host_call`. See
(global_step, *args)
source not stored for this graph (policy: none)
nothing calls this directly
no outgoing calls
no test coverage detected