Add a new measurement.

        The measurement will be processed by the MongoDB* observer
        during a heartbeat event.
        Other observers are not yet supported.

        :param name: The name of the metric, e.g. training.loss
        :param value: The measured value
        :param step: The step number (integer), e.g. the iteration number
                    If not specified, an internal counter for each metric
                    is used, incremented by one.

def log_scalar(self, name, value, step=None):
        """
        Add a new measurement.

        The measurement will be processed by the MongoDB* observer
        during a heartbeat event.
        Other observers are not yet supported.

        :param name: The name of the metric, e.g. training.loss
        :param value: The measured value
        :param step: The step number (integer), e.g. the iteration number
                    If not specified, an internal counter for each metric
                    is used, incremented by one.
        """
        # Method added in change https://github.com/chovanecm/sacred/issues/4
        # The same as Run.log_scalar
        return self.current_run.log_scalar(name, value, step)