Apply refactoring to root package bfxapi.

bfxapi/client.py

@@ -1,39 +1,27 @@
 from .rest import BfxRestInterface
 from .websocket import BfxWebsocketClient
+from .urls import REST_HOST, WSS_HOST
 
 from typing import List, Optional
 
-from enum import Enum
-
-class Constants(str, Enum):
-    REST_HOST = "https://api.bitfinex.com/v2"
-    PUB_REST_HOST = "https://api-pub.bitfinex.com/v2"
-    STAGING_REST_HOST = "https://api.staging.bitfinex.com/v2"
-
-    WSS_HOST = "wss://api.bitfinex.com/ws/2"
-    PUB_WSS_HOST = "wss://api-pub.bitfinex.com/ws/2"
-    STAGING_WSS_HOST = "wss://api.staging.bitfinex.com/ws/2"
-
 class Client(object):
     def __init__(
             self,
-            REST_HOST: str = Constants.REST_HOST,
-            WSS_HOST: str = Constants.WSS_HOST,
+            REST_HOST: str = REST_HOST,
+            WSS_HOST: str = WSS_HOST,
             API_KEY: Optional[str] = None,
             API_SECRET: Optional[str] = None,
             filter: Optional[List[str]] = None,
             log_level: str = "INFO"
     ):
-        credentials = { 
-            "API_KEY": API_KEY, 
-            "API_SECRET": API_SECRET, 
-            "filter": filter 
-        }
+        credentials = None
+
+        if API_KEY and API_SECRET:
+            credentials = { "API_KEY": API_KEY, "API_SECRET": API_SECRET, "filter": filter }
 
         self.rest = BfxRestInterface(
             host=REST_HOST,
-            API_KEY=API_KEY,
-            API_SECRET=API_SECRET
+            credentials=credentials
         )
 
         self.wss = BfxWebsocketClient(