client: cleanup

client/Retriever.py

@@ -1,16 +1,17 @@
 import logging
+from abc import ABC, abstractmethod
 from typing import Dict
 
 from client.httpclient import HTTPClient, BUFSIZE, IncompleteResponse, InvalidResponse, UnsupportedEncoding
 
 
-class Retriever:
+class Retriever(ABC):
     client: HTTPClient
-    headers: Dict[str, str]
 
     def __init__(self, client: HTTPClient):
         self.client = client
 
+    @abstractmethod
     def retrieve(self):
         pass
 
@@ -95,7 +96,7 @@ class ChunkedRetriever(Retriever):
 
     def retrieve(self):
         while True:
-            chunk_size = self._get_chunk_size()
+            chunk_size = self.__get_chunk_size()
             logging.debug("chunk-size: %s", chunk_size)
             if chunk_size == 0:
                 self.client.reset_request()
@@ -108,7 +109,7 @@ class ChunkedRetriever(Retriever):
             self.client.read_line()  # remove CRLF
         return b""
 
-    def _get_chunk_size(self):
+    def __get_chunk_size(self):
         line = self.client.read_line()
         sep_pos = line.find(";")
         if sep_pos >= 0: