pub fn parse_request(line: &str) -> Result<Request, RequestError>Expand description
Parses one request line, telling a malformed line from an unrecognised command from bad arguments, each of which the spec answers with a different code.
Not JSON, not an object, or missing id or cmd is ErrorCode::InvalidRequest with
id null; an unrecognised cmd.type is ErrorCode::UnknownCommand; anything else
is ErrorCode::InvalidParams.