style code correctly

Styled code with fenced code blocks and syntax highlighting.

Day-3/README.md

@@ -10,7 +10,9 @@ Here is one approach to building your function:
 
 This line of code is how you can return heads:
 
-    return "heads"
+```python
+return "heads"
+```
 
 That's it! Test it out and see how many times can your program flip a coin a second.
 
@@ -25,12 +27,16 @@ This program uses an array named totals. An array is a variable that remembers a
 
 This is how you can set a specific slot in the array. In this example we are setting spot 5 (remember it counts starting at zero) to be 99.
 
-        totals[5] = 99
+```python
+totals[5] = 99
+```
 
 This is how we can look up what the number is in a spot and print it out. This would print 99
 
-        print totals[5]
-        
+```python
+print totals[5]
+```
+
 Your job is to complete the dice_roll() function. It should roll two 6-sided dice and add the rolls together. It should return their total.
 
 That's it! Test it and see if it is faster or slower than the coin flip program.