if and unless statements are identical in sexpworld

explanations/if.md

@@ -1,8 +1,11 @@
-## `if` statement
+## `if`/`unless` statement
 
 
+The `if` statement is used for when we want to conditionally run code. 
 
-The `if` statement is used for when we want to conditionally run code. A common `if` syntax is this:
+`unless` is the opposite of `if`. Where `if` will run the code if it evaluates to something that is not `nil` or `false`, `unless` will run its contained code _only_ if the condition evaluates to `nil` or `false`.
+
+A common `if` syntax is this:
 
     if condition then
       conditional_code
@@ -26,4 +29,5 @@ A shorter way to write this would be to use a _ternary statement_, which looks l
 
 In this example the `?` indicates the beginning of the code to run when the `if` evaluates to `true`. After that code, we use `:` to denote what code should be ran if the `condition` evaluates to `false`.
 
-**Please note**: `if` statements that can be condensed to one line will be output as ternary examples, where as multi-lined `if` statements will be output as such with `then` after the condition.
+
+**Please note**: `if` statements that can be condensed to one line will be output as ternary examples, where as multi-lined `if` statements will be output as such with `then` after the condition.

fixtures/if.rb

@@ -5,4 +5,4 @@
   what
 else
   them
-end
+end