Storage slot read, Optimism. Read one raw storage slot of a contract on Optimism (eth_getStorageAt): the 32-byte word, as a number and, when it holds one, as an address. Slot is a decimal index or a 0x 32-byte key (mapping and proxy slots). Use to inspect contract state that has no getter, owners or implementation pointers; for proxies use op_proxy. A malformed address or slot is rejected with 400, uncharged.