'Merge split adjustments with the dict containing overwrites.
Parameters
pre : dict[str -> dict[int -> list]]
The adjustments that occur before the split-adjusted-asof-date.
post : dict[str -> dict[int -> list]]
The adjustments that occur after the split-adjusted-asof-date.
overwrites : dict[str -> dict[int -> list]]
The overwrites across all time. Adjustments will be merged into
this dictionary.
requested_split_adjusted_columns : list of str
List of names of split adjusted columns that are being requested.'

def merge_split_adjustments_with_overwrites(self, pre, post, overwrites, requested_split_adjusted_columns):

    for column_name in requested_split_adjusted_columns:
        if pre:
            for ts in pre[column_name]:
                add_new_adjustments(overwrites, pre[column_name][ts], column_name, ts)
        if post:
            for ts in post[column_name]:
                add_new_adjustments(overwrites, post[column_name][ts], column_name, ts)
