Update 641-language-def.markdown

Author: Joe7M

_build/reference/641-language-def.markdown

@@ -1,30 +1,28 @@
 # DEF
 
-> DEF name[(par1[,...])] = expression
+> DEF name[(par1 [, ... , parN])] = expression
 
-Defines a single line function. 
+Defines a single line function with the function name `name` and the parameters `par1` to `parN`. `expression` is a valid SmallBASIC expression returning a value. 
 
 See FUNC for multiline functions and SUB for multiline subroutines.
 
-Example 1: Function with one parameter
+### Example 1: Function with one parameter
 
-~~~
+```
 def f(x) = 2*x+3
-
 print f(3)
-~~~
+```
 
-Example 2: Function with two parameters
+### Example 2: Function with two parameters
 
-~~~
+```
 def f(x,y) = 2*x + 3*sin(y)
-
 print f(1,2)
-~~~
+```
 
-Example 3: Random number between low and high
+### Example 3: Random number between low and high
 
-~~~
+```
 ' A function for random integer numbers between low and high (inclusive)
 DEF randi(lo, hi) = (RND * (hi - lo + 1))\1 + lo
 
@@ -33,12 +31,11 @@ DEF randf(lo, hi) = (RND * (hi - lo + 1)) + lo
 
 print randi(0, 100)
 print randf(0, 100)
-~~~
+```
 
-Example 4: DEF and LOCAL
-
-~~~
+### Example 4: DEF and LOCAL
 
+```
 ' DEF and LOCAL.bas  SmallBASIC 0.12.2 [B+=MGA] 2016-04-06
 'can I use DEF locally in a sub without interfering with main variable or DEF names
 def aboutMe() = "I am texting from main code."
@@ -52,7 +49,6 @@ sub mySub()
   def aboutMe() = "I am texting from mySub."
 ? "Hi, ";aboutMe
 end
-
-~~~
+```