Fix spelling of the word occurrence

appengine/chromium_try_flakes/model/flake.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import datetime
 
 from google.appengine.ext import ndb
 
 from model.build_run import BuildRun
 
-# A particular occurance of a single flake occuring.
-class FlakeOccurance(ndb.Model):
+# A particular occurrence of a single flake occuring.
+class FlakeOccurrence(ndb.Model):
   # step name, i.e. browser_tests
   name = ndb.StringProperty(required=True)
   # failre, i.e. FooTest.Bar
   failure = ndb.StringProperty(required=True)
 
 
 # Represents a patchset with a successful and failed try run for a particular
 # builder. The flaky failed run can have multiple different flakes that cause
-# it to turn red, each represented by a FlakeOccurance.
+# it to turn red, each represented by a FlakeOccurrence.
 class FlakyRun(ndb.Model):
   failure_run = ndb.KeyProperty(BuildRun, required=True)
   # A copy of failure_run.time_started to reduce lookups.
   failure_run_time_started = ndb.DateTimeProperty(default=datetime.datetime.max)
   # A copy of failure_run.time_finished to reduce lookups.
   failure_run_time_finished = ndb.DateTimeProperty(required=True)
   success_run = ndb.KeyProperty(BuildRun, required=True)
-  flakes = ndb.StructuredProperty(FlakeOccurance, repeated=True)
+  flakes = ndb.StructuredProperty(FlakeOccurrence, repeated=True)
   comment = ndb.StringProperty()
 
 
 # Represents a step that flakes. The name could be a test_suite:test name (i.e.
 # unit_tests:FooTest), a ninja step in case of compile flake, etc... This entity
 # groups together all the occurrences of this flake, with each particular
 # instance of a flake being represented by a FlakyRun.
 class Flake(ndb.Model):
   name = ndb.StringProperty(required=True)
   occurrences = ndb.KeyProperty(FlakyRun, repeated=True)
@@ skipping 29 matching lines @@
 # tracker and prevent too many updates filed. The FlakeUpdateSingleton entity is
 # a singleton and all FlakyUpdate entities should be child entities of this
 # singleton entity, which allows us to query all of them within a single
 # transaction.
 class FlakeUpdateSingleton(ndb.Model):
   pass
 
 
 class FlakeUpdate(ndb.Model):
   time_updated = ndb.DateTimeProperty(auto_now_add=True)