Made the code cleanup changes - mostly nit changes

ml-agents/mlagents/trainers/lesson_controller.py

-import os
+import logging
-
-import logging
-class LessonController(object):
+class LessonController:
     def __init__(self, location):
         """
         Initializes a Curriculum object.
         try:
             with open(location) as data_file:
-                self.data = yaml.load(data_file)
+                data = yaml.load(data_file)
-        self.check_keys(location)
-        self.measure = self.data["measure"]
-        self.thresholds = self.data["thresholds"]
-        self.min_lesson_length = self.data["min_lesson_length"]
+        self.check_keys(data, location)
+        self.measure = data["measure"]
+        self.thresholds = data["thresholds"]
+        self.min_lesson_length = data["min_lesson_length"]
+        self.signal_smoothing = data["signal_smoothing"]
+        self.test_lesson_length = (data["test_lesson_length"] 
+                                if "test_lesson_length" in data 
+                                else 1000)
-    def check_keys(self, location):
+    def check_keys(self, data, location):
         for key in [
             "measure",
             "thresholds",
-            if key not in self.data:
+            if key not in data:
                 raise LessonControllerError(
                     "{0} does not contain a " "{1} field.".format(location, key)
                 )
         :param measure_val: A dict of brain name to measure value.
         :return Whether the lesson was incremented.
         """
-        if not self.data or not measure_val or math.isnan(measure_val):
+        if (not measure_val) or math.isnan(measure_val):
-        if self.data["signal_smoothing"]:
+        if self.signal_smoothing:
-            if measure_val >= self.data["thresholds"][self.lesson_num]:
+            if measure_val >= self.thresholds[self.lesson_num]:
                     self.lesson_num += 1
                     logger.info(
                         "Lesson changed. Now in lesson {0}".format(