use constant

EIPS/eip-2935.md

@@ -41,7 +41,7 @@ def process_block_hash_history(block :Block, state: State):
     # If this is the first fork block, add the parent's direct 255 ancestors as well
     if block.parent.timestamp < FORK_TIMESTAMP:
         ancestor = block.parent
-        for i in range(255):
+        for i in range(HISTORY_SERVE_WINDOW - 1):
             # stop at genesis block
             if ancestor.number == 0:
                 break
@@ -50,7 +50,7 @@ def process_block_hash_history(block :Block, state: State):
             state.insert_slot(HISTORY_STORAGE_ADDRESS, ancestor.number, ancestor.hash)
 ```
 
-Note that if this is the fork block, then it persists the additional requisite history that could be needed while resolving `BLOCKHASH` opcode for all of the `256` ancestors (up untill the genesis).
+Note that if this is the fork block, then it persists the additional requisite history that could be needed while resolving `BLOCKHASH` opcode for all of the `HISTORY_SERVE_WINDOW` ancestors (up untill genesis).
 
 For resolving the `BLOCKHASH` opcode this fork onwards (`block.timestamp > FORK_TIMESTAMP`), switch the logic to: