Gas history, Optimism gas price. Gas price history on Optimism (eth_feeHistory): base fee in gwei for each of the last N blocks (5-100, default 20), how full each block was, and the 10th, 50th and 90th percentile priority fees, with the low, average and high base fee over the window. Use to judge whether fees are rising, pick a priority fee or time a transaction; for the current price alone use op_gas.