code: def get_lock_amount_after_fees(
          lock: HashTimeLockState,
          payee_channel: NettingChannelState,
  ) -> PaymentWithFeeAmount:
      
      return PaymentWithFeeAmount(lock.amount - payee_channel.mediation_fee)
docs: Return the lock.amount after fees are taken.
  
      Fees are taken only for the outgoing channel, which is the one with
      collateral locked from this node.