Adding variable EMA period to MASS Index

[joonis]

The EMA period of MASS Index is hardcoded to 9.
It should be variable by passing it as an option.

[codeplea]

What do other charting libraries do?

Do most charting programs allow this as an option?

Most documentation I see says that Mass Index uses a fixed EMA period of 9. e.g. https://en.wikipedia.org/wiki/Mass_index

[joonis]

If you are working with intervals other than days (eg. hours or even minutes), it is required to adjust the ema period.

There are libs with a variable period:
https://technical-analysis-library-in-python.readthedocs.io/en/latest/ta.html#ta.trend.mass_index