added curses app that follows candles

setup.py

@@ -14,7 +14,7 @@
             'v20-account-changes = account.changes:main',
             'v20-account-configure = account.configure:main',
             'v20-instrument-candles = instrument.candles:main',
-            'v20-instrument-candles-follow = instrument.candles_follow:main',
+            'v20-instrument-candles-poll = instrument.candles_poll:main',
         ]
     }
 )

src/instrument/candles.py

@@ -26,7 +26,7 @@ def main():
     parser.add_argument(
         "--instrument",
         type=common.arg_helper.instrument,
-        default=None,
+        required=True,
         help="The instrument to get candles for"
     )
 

src/instrument/candles_follow.py → src/instrument/candles_poll.py

@@ -39,7 +39,7 @@ def update_candles(self, candles):
 
         # Candles haven't changed
         if new.time == last.time and new.volume == last.time:
-            return
+            return False
 
         # Update last candle
         self.candles[-1] = candles.pop(0)
@@ -50,6 +50,8 @@ def update_candles(self, candles):
         # Get rid of the oldest candles
         self.candles = self.candles[-self.max_candle_count():]
 
+        return True
+
     def max_candle_count(self):
         return self.height - 3
 
@@ -223,9 +225,8 @@ def run(stdscr):
 
         candles = response.get("candles", 200)
 
-        printer.update_candles(candles)
-
-        printer.render()
+        if printer.update_candles(candles):
+            printer.render()
 
 if __name__ == "__main__":
     main()