Revisit pylint warnings.

src/_dns.py

-# pylint: disable=import-error,invalid-name
-import dns.resolver
+import dns.resolver  # pylint: disable=import-error
 import utils
 
 
@@ -11,7 +10,9 @@ def get_resolvers():
     """Return a list of resolvers for each nameserver in the DNS zone."""
     default_resolver = dns.resolver.Resolver()
     resolvers = []
-    for ns in default_resolver.query(DOMAIN, "NS"):
+    for ns in default_resolver.query(  # pylint: disable=invalid-name
+        DOMAIN, "NS"
+    ):
         for address in default_resolver.query(ns.to_text()):
             resolver = dns.resolver.Resolver(configure=False)
             resolver.nameservers = [address.to_text()]
@@ -25,9 +26,9 @@ RESOLVERS = get_resolvers()
 def cross_query(qname, rdtype="A"):
     """Return all of the answers from all nameservers."""
     answers = set()
-    for r in RESOLVERS:
-        for a in r.query(qname, rdtype):
-            answers.add(a)
+    for resolver in RESOLVERS:
+        for address in resolver.query(qname, rdtype):
+            answers.add(address)
     return answers
 
 
@@ -39,9 +40,9 @@ def validate_soa():
         return [False, "SOA records don't match."]
 
     try:
-        r = soas.pop()
-        r.mname.to_text()
-    except Exception as e:  # pylint: disable=broad-except
+        record = soas.pop()
+        record.mname.to_text()
+    except Exception as e:  # pylint: disable=broad-except,invalid-name
         print(str(e))
         return [False, "SOA record is invalid."]
 
@@ -55,11 +56,11 @@ def validate_mx():
         return [False, "MX records don't match."]
 
     try:
-        r = mxs.pop()
-        ips = cross_query(r.exchange.to_text())
+        record = mxs.pop()
+        ips = cross_query(record.exchange.to_text())
         if len(ips) > 1:
             return [False, "MX records don't match."]
-    except Exception as e:  # pylint: disable=broad-except
+    except Exception as e:  # pylint: disable=broad-except,invalid-name
         print(str(e))
         return [False, "MX record is invalid."]
 
@@ -68,12 +69,12 @@ def validate_mx():
 
 def validate_subdomains():
     """Validate important subdomains."""
-    for d in SUBDOMAINS:
+    for domain in SUBDOMAINS:
         try:
-            ips = cross_query(d)
+            ips = cross_query(domain)
             if len(ips) > 1:
-                return [True, f"Domain {d} records don't match."]
-        except Exception as e:  # pylint: disable=broad-except
+                return [True, f"Domain {domain} records don't match."]
+        except Exception as e:  # pylint: disable=broad-except,invalid-name
             print(str(e))
             return [False, "Failed to validate domain {d}."]
     return [True, "Subdomains validated."]
@@ -81,8 +82,8 @@ def validate_subdomains():
 
 def handler(event, context):  # pylint: disable=unused-argument
     """Lambda event handler."""
-    for c in [validate_soa, validate_mx, validate_subdomains]:
-        success, message = c.__call__()
+    for check in [validate_soa, validate_mx, validate_subdomains]:
+        success, message = check.__call__()
         print(message)
         if not success:
             utils.publish(message)

src/mta_sts.py

-# pylint: disable=invalid-name
 from utils import check_urls
 
 

src/utils.py

-# pylint: disable=import-error
 import os
-import boto3
-import requests
+import boto3  # pylint: disable=import-error
+import requests  # pylint: disable=import-error
 
 
 TOPIC_ARN = os.getenv("TOPIC_ARN")