ERC20 option, and its name comes from the TradFi term for an option with a specific underlying token, option type (Put or Call) expiration date, and strike price. Each Series has an associated bToken and wToken which represent the long and short position, respectively, in the Series. The SeriesController manages the lifecycle of all Series, from Series creation in SeriesController.createSeries, the minting of bToken and wToken in SeriesController.mintOptions, to the burning of bToken and wToken in SeriesController.exerciseOption, SeriesController.claimCollateral, and SeriesController.closePosition.uint64 called the seriesId. The SeriesController uses a monotonically increasing index for each new Series is creates, and stores them in the series array.MinterAmm, must transfer into the SeriesController the full collateral necessary to fulfill the option's obligation to buy (Calls) or sell (Puts) the underlying token. For instance, to mint 1.5 unit of bToken on a WBTC Call Series with expiration of Friday 8am July 2nd 2021 and a strike price of $60,000, the seller must first call ERC20.approve and give the SeriesController an allowance of 1.5 WBTC. If instead of a Call, this Series was a Put but all the other parameters remained the same, then the seller would first need to ERC20.approve the SeriesController for 1.5 * $60,000 = 90,0000 USDC. This collateral ensures that no matter what how the price of the underlying token changes, the SeriesController will always be able to redeem option tokens for their correct payout.expirationDatetokensunderlyingToken, priceToken, and collateralToken for this Series