Reverting unnecessary change in previous commit

This reverts the changes made in 17655ce to 3 specific files as the
changed introduced by 2to3 script are not required for the code to run
in Python 3.

This has been tested locally in a Jupyter notebook running Python 3.7.6

REF:
    - 17655ce

	modified:   code/Ecosystem-Chapter_32_Language_Specifics.py
	modified:   code/Low_Level_APIs-Chapter_12_RDD_Basics.py
	modified:   code/Low_Level_APIs-Chapter_13_Advanced_RDDs.py

code/Ecosystem-Chapter_32_Language_Specifics.py

@@ -1,5 +1,5 @@
 import pandas as pd
-df = pd.DataFrame({"first":list(range(200)), "second":list(range(50,250))})
+df = pd.DataFrame({"first":range(200), "second":range(50,250)})
 
 
 # COMMAND ----------

code/Low_Level_APIs-Chapter_12_RDD_Basics.py

@@ -62,7 +62,7 @@ def startsWithS(individual):
 
 # COMMAND ----------
 
-spark.sparkContext.parallelize(list(range(1, 21))).reduce(lambda x, y: x + y) # 210
+spark.sparkContext.parallelize(range(1, 21)).reduce(lambda x, y: x + y) # 210
 
 
 # COMMAND ----------

code/Low_Level_APIs-Chapter_13_Advanced_RDDs.py

@@ -25,17 +25,16 @@
 
 # COMMAND ----------
 
-list(keyword.keys()).collect()
-list(keyword.values()).collect()
+keyword.keys().collect()
+keyword.values().collect()
 
 
 # COMMAND ----------
 
 import random
-from functools import reduce
 distinctChars = words.flatMap(lambda word: list(word.lower())).distinct()\
   .collect()
-sampleMap = dict([(c, random.random()) for c in distinctChars])
+sampleMap = dict(map(lambda c: (c, random.random()), distinctChars))
 words.map(lambda word: (word.lower()[0], word))\
   .sampleByKey(True, sampleMap, 6).collect()
 
@@ -48,7 +47,7 @@ def maxFunc(left, right):
   return max(left, right)
 def addFunc(left, right):
   return left + right
-nums = sc.parallelize(list(range(1,31)), 5)
+nums = sc.parallelize(range(1,31), 5)
 
 
 # COMMAND ----------
@@ -122,7 +121,7 @@ def mergeCombinerFunc(vals1, vals2):
 
 # COMMAND ----------
 
-numRange = sc.parallelize(list(range(10)), 2)
+numRange = sc.parallelize(range(10), 2)
 words.zip(numRange).collect()