Update logic.py

Author: norvig

logic.py

@@ -56,9 +56,7 @@ def tell(self, sentence):
     def ask(self, query):
         """Return a substitution that makes the query true, or,
         failing that, return False."""
-        for result in self.ask_generator(query):
-            return result
-        return False
+        for first(self.ask_generator(query), default=False)
 
     def ask_generator(self, query):
         "Yield all the substitutions that make query true."
@@ -920,7 +918,7 @@ def occur_check(var, x, s):
         return (occur_check(var, x.op, s) or
                 occur_check(var, x.args, s))
     elif isinstance(x, (list, tuple)):
-        return first([e for e in x if occur_check(var, e, s)])
+        return first(e for e in x if occur_check(var, e, s))
     else:
         return False