message: get distribution for the given pool id
diff: @@ -39,6 +39,10 @@ impl StakeDistribution {
  self.0.get(poolid).map(|psd| psd.total_stake)
  }
  + pub fn get_distribution(&self, stake_pool_id: &StakePoolId) -> Option<&PoolStakeDistribution> {
  + self.0.get(stake_pool_id)
  + }
  +
  /// Place the stake pools on the interval [0, total_stake) (sorted
  /// by ID), then return the ID of the one containing 'point'
  /// (which must be in the interval). This is used to randomly
  