add a few comments

respodns/ip_info.py

@@ -98,6 +98,8 @@ class IpInfoByIpApi(IpInfoBase):
         )
         query = "\r\n".join(query_lines) + "\r\n\r\n"
 
+        # TODO: only perform DNS lookup once.
+        # TODO: only open connection once if possible (keep-alive).
         reader, writer = await open_connection(self.host, 80)
 
         writer.write(self.encode(query, "strict"))

respodns/top1m.py

@@ -1,5 +1,5 @@
 urltop_default = "http://s3.amazonaws.com/alexa-static/top-1m.csv.zip"
-csvfn_default = "top-1m.csv"
+csvfn_default = "top-1m.csv"  # path within the zip file
 
 one_week = 7 * 24 * 60 * 60  # in seconds
 
@@ -8,6 +8,7 @@ def alive(fp, expiry):
     from os.path import exists, getmtime, getsize
     from time import time
 
+    # 2 is used as a magic number because it's len("\r\n")
     return exists(fp) and time() < getmtime(fp) + expiry and getsize(fp) > 2