tf.contrib.learn.monitors.ExportMonitor.step_begin(step)
Overrides BaseMonitor.step_begin.
When overriding this method, you must call the super implementation.
Args:
step: int, the current value of the global step.
Returns:
A list, the result of every_n_step_begin, if that was called this step, or an empty list otherwise.
Raises:
ValueError: if called more than once during a step.