Deleting an outlier loses the whole row. A gentler fix is capping: any value past a fence is pulled back to sit exactly on that fence.
Write cap_outliers(values). values is a list of numbers, where None marks a missing reading.
quantile(0.25) and quantile(0.75) on the known values only.None as None, in its place.Return a list of the same length as values, with every number rounded to 2 decimal places. There is always at least one known value.