Function ensure_personal_alias

pub fn ensure_personal_alias<OuterOrigin>(
    o: OuterOrigin,
) -> Result<ContextualAlias, BadOrigin>
where
    OuterOrigin: TryInto<Origin, Error = OuterOrigin>,

Ensure that the origin o represents an extrinsic (i.e. transaction) from a personal alias. Returns Ok with the personal alias that signed the extrinsic or an Err otherwise.