Check that the raw value for an asset/date/column triple is as
    expected.

    Used by tests to verify data written by a writer.

def expected_bar_value(asset_id, date, colname):
    """
    Check that the raw value for an asset/date/column triple is as
    expected.

    Used by tests to verify data written by a writer.
    """
    from_asset = asset_id * 100000
    from_colname = OHLCV.index(colname) * 1000
    from_date = (date - PSEUDO_EPOCH).days
    return from_asset + from_colname + from_date