Question about verification function of sample smart contract wallet account from the Ethereum foundation

Contract code: here

EIP documentation: here

I've been studying account abstraction, and I'm confused about where the userOpHash comes from in the contract above. From the way the contract is written along with the EIP documentation provided above, it seems like the owner of the contract is supposed to generate the userOpHash before sending the UserOperation object (from the EIP documentation: "The userOpHash is a hash over the userOp (except signature), entryPoint and chainId."). However, while playing around with Alchemy's "eth_sendUserOperation" function (here), I can't seem to find a place to include the userOpHash (it only has a place for signature which is different). This makes me assume that the hashing is handled by the EntryPoint contract, but I'm not sure at all if this is true. Can someone help explain to me how the hashing is happening and how the verification function in the contract code actually works?