Fixes some typos in Lesson 4 pages (UWPCE-PythonCert#172)

Author: hosungs

source/conf.py

@@ -66,7 +66,7 @@
                "Andy Miles"
                "Rick Riehle",
                "Joseph Schilz",
-               "Joseph Sheedy"
+               "Joseph Sheedy",
                "Hosung Song"
                ]
 

source/exercises/kata_fourteen.rst

@@ -212,7 +212,7 @@ Building the Trigrams dict
 
 So you've got a list of words, and you need to build up a dict like one of the above.
 
-It time to create a python file and start writting some code!
+It's time to create a python file and start writting some code!
 
 .. code-block:: python
 
@@ -244,7 +244,7 @@ So how do you actually build up that dict? That's kind of the point of the exerc
 
 **Looping through the words**
 
-Obviously you need to loop through all the words, so a ``for loop`` makes sense. However, this is a bit tricky. Usually in Python you loop through all the items in a list, and don't worry about the indices:
+Obviously you need to loop through all the words, so a ``for`` loop makes sense. However, this is a bit tricky. Usually in Python you loop through all the items in a list, and don't worry about the indices:
 
 .. code-block:: python
 
@@ -256,23 +256,23 @@ So contrary to the usual practice, an index can be helpful here:
 
 .. code-block:: python
 
-  for i in len(words)-2: # why -2 ?
+  for i in range(len(words)-2): # why -2 ?
      pair = words[i:i + 2]
      follower = words[i + 2]
 
 **Adding a pair to the dict:**
 
 For each pair in the text, you need to add it to the dict. But:
 
-- words[i:i + 2] is a list with two words in it. Can that be used as a key in a dict? (Try it.) If not, how can you make a valid key out of it?
+- ``words[i:i + 2]`` is a list with two words in it. Can that be used as a key in a dict? (Try it.) If not, how can you make a valid key out of it?
 
 - As you loop through the text, you will collect pairs of words. Each time, a given pair may already be in the dict.
 
   - If the pair is not in the dict, you want to put it in the dict, with value being a list with the follower in it::
 
     ("may", "I"): ["wish"]
 
-  - If the pair already is in the dict, then you want to add the follower (the second word in the pair) to the list that's already there
+  - If the pair already is in the dict, then you want to add the follower (the second word in the pair) to the list that's already there::
 
     ("wish", "I"): ["may", "might"]
 
@@ -294,7 +294,7 @@ Using the Trigrams dict
 
 This is the fun part. Once you have a mapping of word pairs to following words, you can build up some new "fake" text. Re-read the previous sections again to remind yourself of the procedure. Here are a couple of additional hints and questions to consider:
 
-- The ```random`` module <https://docs.python.org/3/library/random.html#module-random>`_ is your friend here:
+- The ``random`` module <https://docs.python.org/3/library/random.html#module-random> is your friend here:
 
 .. code-block:: python
 
@@ -357,7 +357,7 @@ Do get the full trigrams code working first, then play with some of the fancier
 Code Structure
 --------------
 
-Break your code down into a handful of separate functions. This way you can test each on its own, and it's easier to refactor one part without messing with the others.  For instance, your __main__ block might look something like:
+Break your code down into a handful of separate functions. This way you can test each on its own, and it's easier to refactor one part without messing with the others.  For instance, your ``__main__`` block might look something like:
 
 .. code-block:: python
 

source/exercises/mailroom-part2.rst

@@ -50,7 +50,7 @@ In the first version of mailroom, you generated a letter to a donor who had just
 
 In this version of your program, add a function (and a menu item to invoke it), that goes through all the donors in your donor data structure, generates a thank you letter for each donor, and writes each letter to disk as a text file.
 
-Your main menu may look something like:
+Your main menu may look something like::
 
   Choose an action:
 

source/modules/DictsAndSets.rst

@@ -57,7 +57,7 @@ Calling the dict type object constructor:
     >>> dict(key1=3, key2= 5)
     {'key1': 3, 'key2': 5}
 
-    # creating and empty dict, and then populating it:
+    # creating an empty dict, and then populating it:
     >>> d = {}
     >>> d['key1'] = 3
     >>> d['key2'] = 5
@@ -181,7 +181,7 @@ Traditionally, dictionaries have had no defined order. See this example from Pyt
 Note how I defined the dict in a natural order, but when it gets printed, or you display the keys, they are in a different order.
 
 However, In cPython 3.6, the internal implementation was changed, and it *does* happen to preserve order. In cPython 3.6, that is considered an implementation detail -- and you should not count on it! However, as of cPython 3.7, dictionaries preserving order will be part of the language specification. This was declared by Guido on the python-dev mailing list on
-`Dec 15, 2017 <https://mail.python.org/pipermail/python-dev/2017-December/151283.html>`
+Dec 15, 2017 <https://mail.python.org/pipermail/python-dev/2017-December/151283.html>.
 
 .. code-block:: ipython
 

source/modules/Files.rst

@@ -107,7 +107,7 @@ Common Idioms
         do_something_with_line()
 
 
-We will learn more about the keyword with later, but for now, just understand
+We will learn more about the keyword ``with`` later, but for now, just understand
 the syntax and the advantage over the try-finally block:
 
 .. code-block:: python
@@ -192,11 +192,11 @@ Absolute paths:
     '/home/chris/secret.txt'
 
 
-Either work with ``open()`` , etc.
+Either works with ``open()`` , etc.
 
 (A working directory only makes sense with command-line programs.)
 
-os module
+``os`` module
 ----------
 
 .. code-block:: python