Max pain daemon:

- To calculate the `max_pain` first we need an expiration date,
get_expiration_dates()` retrieves them and the user then enters one of
the shown, then using the select expiry_date on `get_instruments()` we
are good to build the `oi_by_strikes` important!

- Add `update_oi_by_strikes()`.

- Add `check_if_complete()`.

- `get_max_pain()`: here's where all the action takes place, the
`oi_by_strikes` must be complete to start the calculations,

- Use `maybe_open_oi_feed` for open a oi_feed.

- Add `max_pain_readme.rst`

piker/brokers/deribit/api.py

@@ -122,7 +122,7 @@ def str_to_cb_sym(name: str) -> Symbol:
     quote = base
 
     if option_type == 'put':
-        option_type = PUT 
+        option_type = PUT
     elif option_type == 'call':
         option_type = CALL
     else:
@@ -154,7 +154,7 @@ def piker_sym_to_cb_sym(name: str) -> Symbol:
     quote: str = base
 
     if option_type == 'P' or option_type == 'PUT':
-        option_type = PUT 
+        option_type = PUT
     elif option_type == 'C' or option_type == 'CALL':
         option_type = CALL
     else:
@@ -420,7 +420,7 @@ class Client:
         """
         Get a dict with all expiration dates listed as value and currency as key.
         """
-        
+
         params: dict[str, str] = {
             'currency': currency.upper(),
             'kind': kind,
@@ -744,38 +744,6 @@ async def aio_price_feed_relay(
     the `piker`-side `trio.task` consumers for delivery to consumer
     sub-actors for various subsystems.
 
-    '''
-    async def _trade(
-        trade: Trade,  # cryptofeed, NOT ours from `.venues`!
-        receipt_timestamp: int,
-    ) -> None:
-        '''
-        Proxy-thru `cryptofeed.FeedHandler` "trades" to `piker`-side.
-
-        '''
-        to_trio.send_nowait(('trade', trade))
-
-    async def _l1(
-        book: L1Book,
-        receipt_timestamp: int,
-    ) -> None:
-        '''
-        Relay-thru "l1 book" updates.
-
-        '''
-
-        to_trio.send_nowait(('l1', book))
-
-        # TODO, make this work!
-        # -[ ] why isn't this working in `tractor.pause_from_sync()`??
-        # breakpoint()
-
-    sym: Symbol = piker_sym_to_cb_sym(instrument)
-    '''
-    Relay price feed quotes from the `cryptofeed.FeedHandler` to
-    the `piker`-side `trio.task` consumers for delivery to consumer
-    sub-actors for various subsystems.
-
     '''
     async def _trade(
         trade: Trade,  # cryptofeed, NOT ours from `.venues`!
@@ -807,7 +775,6 @@ async def aio_price_feed_relay(
         DERIBIT,
         channels=[TRADES, L1_BOOK],
         symbols=[sym],
-        symbols=[sym],
         callbacks={
             TRADES: _trade,
             L1_BOOK: _l1
@@ -818,13 +785,10 @@ async def aio_price_feed_relay(
             start_loop=False,
             install_signal_handlers=False
         )
-            install_signal_handlers=False
-        )
 
     # sync with trio
     to_trio.send_nowait(None)
 
-    # run until cancelled
     # run until cancelled
     await asyncio.sleep(float('inf'))
 
@@ -834,14 +798,6 @@ async def open_price_feed(
     instrument: str
 ) -> to_asyncio.LinkedTaskChannel:
 
-    fh: FeedHandler
-    first: None
-    chan: to_asyncio.LinkedTaskChannel
-    async with (
-        maybe_open_feed_handler() as fh,
-        to_asyncio.open_channel_from(
-) -> to_asyncio.LinkedTaskChannel:
-
     fh: FeedHandler
     first: None
     chan: to_asyncio.LinkedTaskChannel
@@ -849,34 +805,28 @@ async def open_price_feed(
         maybe_open_feed_handler() as fh,
         to_asyncio.open_channel_from(
             partial(
-                aio_open_interest_feed_relay,
+                aio_price_feed_relay,
                 fh,
-                instruments,
+                instrument
             )
         ) as (first, chan)
     ):
         yield chan
-        ) as (first, chan)
-    ):
-        yield chan
 
 
 @acm
-async def maybe_open_oi_feed(
+async def maybe_open_price_feed(
-    instruments: list[Symbol], 
+    instrument: str
 ) -> trio.abc.ReceiveStream:
 
     # TODO: add a predicate to maybe_open_context
     feed: to_asyncio.LinkedTaskChannel
-    feed: to_asyncio.LinkedTaskChannel
     async with maybe_open_context(
-        acm_func=open_oi_feed,
+        acm_func=open_price_feed,
         kwargs={
             'instrument': instrument.split('.')[0]
-            'instrument': instrument.split('.')[0]
         },
         key=f'{instrument.split('.')[0]}-price',
-        key=f'{instrument.split('.')[0]}-price',
     ) as (cache_hit, feed):
         if cache_hit:
             yield broadcast_receiver(feed, 10)
@@ -884,6 +834,7 @@ async def maybe_open_oi_feed(
             yield feed
 
 
+
 async def aio_open_interest_feed_relay(
     fh: FeedHandler,
     instruments: list[Symbol],
@@ -955,7 +906,7 @@ async def aio_open_interest_feed_relay(
 
 @acm
 async def open_oi_feed(
-    instruments: list[Symbol], 
+    instruments: list[Symbol],
 ) -> to_asyncio.LinkedTaskChannel:
 
     fh: FeedHandler
@@ -976,7 +927,7 @@ async def open_oi_feed(
 
 @acm
 async def maybe_open_oi_feed(
-    instruments: list[Symbol], 
+    instruments: list[Symbol],
 ) -> trio.abc.ReceiveStream:
 
     # TODO: add a predicate to maybe_open_context