pub trait VarlinkInterface {
fn get_info(&self, call: &mut dyn Call_GetInfo) -> Result<()>;
fn get_interface_description(
&self,
call: &mut dyn Call_GetInterfaceDescription,
interface: String
) -> Result<()>;
fn call_upgraded(
&self,
_call: &mut Call<'_>,
_bufreader: &mut dyn BufRead
) -> Result<Vec<u8>> { ... }
}