history_container.py 文件源码

def __new__(cls, field=None, frequency_delta=None, length_delta=None):
        """
        field is a new field that was added.
        frequency is a FrequencyDelta representing a new frequency was added.
        length is a bar LengthDelta which is a frequency and a bar_count.
        If any field is None, then no change occurred of that type.
        """
        return super(HistoryContainerDelta, cls).__new__(
            cls, field, frequency_delta, length_delta,
        )