.deribit.venues: add todo for an ideal `OptionPair.expiry` fmt/value

piker/brokers/deribit/venues.py

@@ -26,8 +26,6 @@ from typing import (
 )
 from decimal import Decimal
 
-from msgspec import field
-
 from piker.types import Struct
 
 
@@ -115,9 +113,13 @@ class OptionPair(Pair, frozen=True):
     # NOTE: see `.data._symcache.SymbologyCache.load()` for why
     ns_path: str = 'piker.brokers.deribit:OptionPair'
 
+    # TODO, impl this without the MM:SS part of
+    # the `'THH:MM:SS..'` etc..
     @property
     def expiry(self) -> str:
-        iso_date = pendulum.from_timestamp(self.expiration_timestamp / 1000).isoformat()
+        iso_date = pendulum.from_timestamp(
+            self.expiration_timestamp / 1000
+        ).isoformat()
         return iso_date 
 
     @property