diff --git a/luigi/task.py b/luigi/task.py
index <HASH>..<HASH> 100644
--- a/luigi/task.py
+++ b/luigi/task.py
@@ -17,6 +17,7 @@ import logging
 import parameter
 import warnings
 import traceback
+import itertools
 import pyparsing as pp
 
 Parameter = parameter.Parameter
@@ -472,11 +473,7 @@ class Task(object):
             warnings.warn("Task %r without outputs has no custom complete() method" % self)
             return False
 
-        for output in outputs:
-            if not output.exists():
-                return False
-        else:
-            return True
+        return all(itertools.imap(lambda output: output.exists(), outputs))
 
     def output(self):
         """The output that this Task produces.
Simplify Task.complete()

Just using standard functional tools. Note that it's necessary to use
itertools to not change the semantics, in case one of the exists()
methods have side effects.