Const
Ref: https://github.com/paritytech/polkadot-sdk/blob/36957d676033b23b46edb66e6d7dcd13da11e19a/substrate/frame/transaction-payment/rpc/runtime-api/src/lib.rs#L26-L36
Ref: https://github.com/paritytech/polkadot-sdk/blob/36957d676033b23b46edb66e6d7dcd13da11e19a/substrate/frame/transaction-payment/rpc/runtime-api/src/lib.rs#L26-L36