fix flake8 issues, clarify comment

sshuttle/cmdline.py

@@ -48,10 +48,11 @@ def main():
             return hostwatch.hw_main(opt.subnets, opt.auto_hosts)
         else:
             # parse_subnetports() is used to create a list of includes
-            # and excludes. It returns a list of one or more items for
-            # each subnet. It returns a list since "-x example.com"
-            # might find that example.com has multiple IP addresses. Here,
-            # we flatten these lists.
+            # and excludes. It is called once for each parameter and
+            # returns a list of one or more items for each subnet (it
+            # can return more than one item when a hostname in the
+            # parameter resolves to multiple IP addresses. Here, we
+            # flatten these lists.
             includes = [item for sublist in opt.subnets+opt.subnets_file
                         for item in sublist]
             excludes = [item for sublist in opt.exclude for item in sublist]

sshuttle/options.py

@@ -67,7 +67,7 @@ def parse_subnetport(s):
                         "of /%s is not supported. Specify the IP "
                         "addresses directly if you wish to specify "
                         "a mask." % (host, cidr))
-        
+
         # Warn if a domain has multiple IPs of the same type (IPv4 vs
         # IPv6) and the mask is applied to all of the IPs.
         if len(addr_v4) > 1 or len(addr_v6) > 1:
@@ -81,7 +81,7 @@ def parse_subnetport(s):
 
         # Largest possible slash value we can use with this IP:
         max_cidr = 32 if family == socket.AF_INET else 128
-        
+
         if cidr is None:  # if no mask, use largest mask
             cidr_to_use = max_cidr
         else:   # verify user-provided mask is appropriate
@@ -94,7 +94,6 @@ def parse_subnetport(s):
         rv.append((family, addr[0], cidr_to_use,
                    int(fport or 0), int(lport or fport or 0)))
 
-
     return rv
 
 
@@ -124,7 +123,8 @@ def parse_ipport(s):
         raise Fatal('Unable to resolve address: %s' % host)
 
     if len(addrinfo) > 1:
-        print("WARNING: Host %s has more than one IP, only using one of them." % host)
+        print("WARNING: Host %s has more than one IP, only using one of them."
+              % host)
 
     family, _, _, _, addr = min(addrinfo)
     # Note: addr contains (ip, port)