an API to external a UserOperation with paymaster info
class PaymasterAPI {}
function constructor(): PaymasterAPI;
let returnType: PaymasterAPI;
function getPaymasterAndData( userOp: Partial<UserOperationStruct>,): Promise<PaymasterResult>;
a partially-filled UserOperation (without signature and paymasterAndData note that the "preVerificationGas" is incomplete: it can't account for the paymasterAndData value, which will only be returned by this method..
let userOp: Partial<UserOperationStruct>;
let returnType: Promise<PaymasterResult>;
the value to put into the PaymasterAndData, undefined to leave it empty