Meats: Backwardation/Cantango

MEATS: Live Cattle , Feeder Cattle, Lean Hogs (LE, GF , HE)
Quickly visualize carrying charge market vs backwardized market by comparing the price of the next 2 years of futures contracts.
Carrying charge (contract prices increasing into the future) = normal, representing the costs of carrying/storage of a commodity. When this is flipped to Backwardation (contract prices decreasing into the future): its a bullish sign: Buyers want this commodity, and they want it NOW.

Note: indicator does NOT map to time axis in the same way as price; it simply plots the progression of contract months out into the future; left to right; so timeframe DOESN'T MATTER for this plot
There's likely some more efficient way to write this; e.g. when plotting for Live Cattle (LE); 8 of the security requests are redundant; but they are still made; and can make this slower to load
TO UPDATE(once a year will do): in REQUEST CONTRACTS section, delete old contracts (top) and add new ones (bottom). Then in PLOTTING section, Delete old contract labels (bottom); add new contract labels (top); adjust the X in 'bar_index-(X+_historical)' numbers accordingly

This is one of three similar indicators: Meats | Metals | Grains
-If you want to build from this; to work on other commodities ; be aware that Tradingview limits the number of contract calls to 40 (hence the 3 seperate indicators)

Tips:
-Right click and reset chart if you can't see the plot; or if you have trouble with the scaling.
-Right click and add to new scale if you prefer this not to overlay directly on price. Or move to new pane below.

--Added historical input: input days back in time; to see the historical shape of the Futures curve via selecting 'days back' snapshot
updated 15th June 2022
© twingall

Release Notes:

-updated contracts

Release Notes:

-added function to detect if contract is expired: Now will stop showing contracts once they expire, unless using the backtesting 'snapshot' mode