fromErrToOptionConvert to Some(E) if input is Err(E). Otherwise, return None. function fromErrToOption<T, E>(input: Result<T, E>): Option<E>;§fromErrToOption<T, E>(input: Result<T, E>): Option<E>[src]§Type Parameters§T[src]§E[src]§Parameters§input: Result<T, E>[src]§Return Type§Option<E>[src]