uasyncio: Add __repr__() for StreamReader/StreamWriter.

uasyncio/uasyncio.py

@@ -211,6 +211,9 @@ class StreamReader:
         log.debug("StreamReader.readline(): res: %s", res)
         return res
 
+    def __repr__(self):
+        return "<StreamReader %r>" % self.s
+
 
 class StreamWriter:
 
@@ -244,6 +247,9 @@ class StreamWriter:
         yield IOWriteDone(self.s)
         self.s.close()
 
+    def __repr__(self):
+        return "<StreamWriter %r>" % self.s
+
 
 def open_connection(host, port):
     log.debug("open_connection(%s, %s)", host, port)