diff --git a/specs/phase0/fork-choice.md b/specs/phase0/fork-choice.md
index 920746da2..4d1c967ef 100644
--- a/specs/phase0/fork-choice.md
+++ b/specs/phase0/fork-choice.md
@@ -32,6 +32,7 @@
     - [`on_tick`](#on_tick)
     - [`on_block`](#on_block)
     - [`on_attestation`](#on_attestation)
+    - [`on_attester_slashing`](#on_attester_slashing)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 <!-- /TOC -->
@@ -181,7 +182,7 @@ def get_latest_attesting_balance(store: Store, root: Root) -> Gwei:
     attestation_score = Gwei(sum(
         state.validators[i].effective_balance for i in active_indices
         if (i in store.latest_messages
-            and not i in store.has_equivocated
+            and i not in store.has_equivocated
             and get_ancestor(store, store.latest_messages[i].root, store.blocks[root].slot) == root)
     ))
     if store.proposer_boost_root == Root():
@@ -469,7 +470,8 @@ def on_attestation(store: Store, attestation: Attestation, is_from_block: bool=F
 ```python
 def on_attester_slashing(store: Store, attester_slashing: AttesterSlashing) -> None:
     """
-    Run ``on_attester_slashing`` upon receiving a new ``AttesterSlashing`` from either within a block or directly on the wire.
+    Run ``on_attester_slashing`` upon receiving a new ``AttesterSlashing`` from either within a block or directly 
+    on the wire.
     """
     attestation_1 = attester_slashing.attestation_1
     attestation_2 = attester_slashing.attestation_2
diff --git a/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_get_head.py b/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_get_head.py
index 469c8e9d4..1f37625a8 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_get_head.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/fork_choice/test_get_head.py
@@ -368,7 +368,7 @@ def test_discard_equivocations(spec, state):
 
     # Build equivocating attestations to feed to store
     state_eqv = state_1.copy()
-    block_eqv = apply_empty_block(spec, state_eqv, state_eqv.slot+1)
+    block_eqv = apply_empty_block(spec, state_eqv, state_eqv.slot + 1)
     attestation_eqv = get_valid_attestation(spec, state_eqv, slot=block_eqv.slot, signed=True)
 
     next_slots(spec, state_1, 1)
@@ -420,4 +420,4 @@ def test_discard_equivocations(spec, state):
         }
     })
 
-    yield 'steps', test_steps
\ No newline at end of file
+    yield 'steps', test_steps