[python/en] some clean up, add a Modulo example

python.html.markdown

@@ -50,17 +50,19 @@ Note: This article applies to Python 3 specifically. Check out [here](http://lea
 10.0 / 3  # => 3.3333333333333335
 
 # Modulo operation
-7 % 3  # => 1
+7 % 3   # => 1
+# i % j have the same sign as j, unlike C
+-7 % 3  # => 2
 
 # Exponentiation (x**y, x to the yth power)
 2**3  # => 8
 
 # Enforce precedence with parentheses
-1 + 3 * 2  # => 7
+1 + 3 * 2    # => 7
 (1 + 3) * 2  # => 8
 
 # Boolean values are primitives (Note: the capitalization)
-True  # => True
+True   # => True
 False  # => False
 
 # negate with not
@@ -126,7 +128,7 @@ b == a            # => True, a's and b's objects are equal
 "This is a string."
 'This is also a string.'
 
-# Strings can be added too! But try not to do this.
+# Strings can be added too
 "Hello " + "world!"  # => "Hello world!"
 # String literals (but not variables) can be concatenated without using '+'
 "Hello " "world!"    # => "Hello world!"
@@ -140,10 +142,9 @@ len("This is a string")  # => 16
 # You can also format using f-strings or formatted string literals (in Python 3.6+)
 name = "Reiko"
 f"She said her name is {name}." # => "She said her name is Reiko"
-# You can basically put any Python statement inside the braces and it will be output in the string.
+# You can basically put any Python expression inside the braces and it will be output in the string.
 f"{name} is {len(name)} characters long." # => "Reiko is 5 characters long."
 
-
 # None is an object
 None  # => None
 
@@ -173,7 +174,6 @@ print("Hello, World", end="!")  # => Hello, World!
 
 # Simple way to get input data from console
 input_string_var = input("Enter some data: ") # Returns the data as a string
-# Note: In earlier versions of Python, input() method was named as raw_input()
 
 # There are no declarations, only assignments.
 # Convention is to use lower_case_with_underscores
@@ -506,7 +506,7 @@ print(contents)
 
 with open('myfile2.txt', "r+") as file:
     contents = json.load(file)       # reads a json object from a file
-print(contents)     
+print(contents)
 # print: {"aa": 12, "bb": 21}
 
 
@@ -919,7 +919,7 @@ class Batman(Superhero, Bat):
 
     def __init__(self, *args, **kwargs):
         # Typically to inherit attributes you have to call super:
-        # super(Batman, self).__init__(*args, **kwargs)      
+        # super(Batman, self).__init__(*args, **kwargs)
         # However we are dealing with multiple inheritance here, and super()
         # only works with the next base class in the MRO list.
         # So instead we explicitly call __init__ for all ancestors.