message: Add `Display` impl for `EraId`.
diff: @@ -13,6 +13,7 @@ use std::{
  use anyhow::Error;
  use casper_types::U512;
  +use fmt::Display;
  use num_traits::AsPrimitive;
  use rand::{CryptoRng, Rng};
  use serde::{Deserialize, Serialize};
  @@ -58,11 +59,17 @@ impl EraId {
  }
  }
  - fn successor(self) -> EraId {
  + pub(crate) fn successor(self) -> EraId {
  EraId(self.0 + 1)
  }
  }
  +impl Display for EraId {
  + fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
  + write!(f, "EraId({})", self.0)
  + }
  +}
  +
  pub(crate) struct Era<I, R: Rng + CryptoRng + ?Sized> {
  /// The consensus protocol instance.
  consensus: Box<dyn ConsensusProtocol<I, ProtoBlock, PublicKey, R>>,
  