fixes

setup.py

@@ -201,7 +201,7 @@ def get_spec(file_name: Path, preset: Dict[str, str], config: Dict[str, str]) ->
                 # NOTE: trim whitespace from spec
                 ssz_objects[current_name] = "\n".join(line.rstrip() for line in source.splitlines())
             else:
-                raise Exception("unrecognized python code element")
+                raise Exception("unrecognized python code element: " + source)
         elif isinstance(child, Table):
             for row in child.children:
                 cells = row.children

specs/altair/beacon-chain.md

@@ -23,6 +23,7 @@
     - [`BeaconBlockBody`](#beaconblockbody)
     - [`BeaconState`](#beaconstate)
   - [New containers](#new-containers)
+    - [`HistoricalBatchSummary`](#historicalbatchsummary)
     - [`SyncAggregate`](#syncaggregate)
     - [`SyncCommittee`](#synccommittee)
 - [Helper functions](#helper-functions)
@@ -204,11 +205,14 @@ class BeaconState(Container):
 
 ### New containers
 
+#### `HistoricalBatchSummary`
 
 ```python
-# The tree roots that make up a phase0 HistoricalBatch making its layout
-# hash_tree_root-compatible.
 class HistoricalBatchSummary(Container):
+    """
+    `HistoricalBatchSummary` matches the components of the phase0 HistoricalBatch
+    making the two hash_tree_root-compatible.
+    """
     block_batch_root: Root
     state_batch_root: Root
 ```

specs/altair/fork.md

@@ -58,7 +58,7 @@ def translate_participation(state: BeaconState, pending_attestations: Sequence[p
             for flag_index in participation_flag_indices:
                 epoch_participation[index] = add_flag(epoch_participation[index], flag_index)
 
-def load_historical_batches(state: BeaconState, pre: BeaconState) -> List[HistoricalBatchSummary, HISTORICAL_ROOTS_LIMIT]:
+def load_historical_batches(pre: BeaconState) -> List[HistoricalBatchSummary, HISTORICAL_ROOTS_LIMIT]:
     # Clients need to recalculate the historical batches from genesis and return
     # them here with the roots of the blocks and states separated. It's assumed
     # most of these are pre-calculated and the rest are stored on-the-fly by
@@ -69,7 +69,7 @@ def load_historical_batches(state: BeaconState, pre: BeaconState) -> List[Histor
 
 def upgrade_to_altair(pre: phase0.BeaconState) -> BeaconState:
     epoch = phase0.get_current_epoch(pre)
-    historical_batches = load_historical_batches()
+    historical_batches = load_historical_batches(pre)
 
     # Tree hash should match since HistoricalBatchSummary is an intermediate step in calculating the phase0 historical root entry
     assert hash_tree_root(historical_batches) == hash_tree_root(pre.historical_roots)