'Fix `Optional` and use `'linear/reverse'` in `OptionPair.venue`'

piker/brokers/deribit/venues.py

@@ -22,6 +22,7 @@ from __future__ import annotations
 import pendulum
 from typing import (
     Literal,
+    Optional,
 )
 from decimal import Decimal
 
@@ -111,7 +112,6 @@ class OptionPair(Pair, frozen=True):
     block_trade_min_trade_amount: int # '25'
     block_trade_commission: float # '0.003'
 
-
     # NOTE: see `.data._symcache.SymbologyCache.load()` for why
     ns_path: str = 'piker.brokers.deribit:OptionPair'
 
@@ -122,7 +122,7 @@ class OptionPair(Pair, frozen=True):
 
     @property
     def venue(self) -> str:
-        return 'option'
+        return f'{self.instrument_type}_option'
 
     @property
     def bs_fqme(self) -> str: