Fix comments

contracts/Proofs.sol

@@ -39,6 +39,10 @@ contract Proofs {
     markers[id] = uint(blockhash(block.number - 1)) % period;
   }
 
+  // Check whether a proof is required at the time of the block with the
+  // specified block number. A proof has to be submitted within the proof
+  // timeout for it to be valid. Whether a proof is required is determined
+  // randomly, but on average it is once every proof period.
   function _isProofRequired(
     bytes32 id,
     uint blocknumber

contracts/Storage.sol

@@ -69,10 +69,6 @@ contract Storage is Contracts, Proofs {
     return _missed(contractId);
   }
 
-  // Check whether a proof is required at the time of the block with the
-  // specified block number. A proof has to be submitted within the proof
-  // timeout for it to be valid. Whether a proof is required is determined
-  // randomly, but on average it is once every proof period.
   function isProofRequired(
     bytes32 contractId,
     uint blocknumber

contracts/TestContracts.sol

@@ -3,6 +3,7 @@ pragma solidity ^0.8.0;
 
 import "./Contracts.sol";
 
+// exposes internal functions of Contracts for testing
 contract TestContracts is Contracts {
 
   function newContract(