use rstd::prelude::Vec; pub trait OperatorProvider<AccountId> { // Make sure `who` has permission to feed data fn can_feed_data(who: &AccountId) -> bool; // return a list of operators fn operators() -> Vec<AccountId>; } impl<AccountId> OperatorProvider<AccountId> for () { fn can_feed_data(_who: &AccountId) -> bool { false } fn operators() -> Vec<AccountId> { Vec::new() } }