anchor.diff:  ])
   ----
   
  -We want to filter out the dogs because we're writing enterprise grade software.
  +We want to filter out the non-dog animals because we're writing enterprise grade software.
   First, let's look at a normal for loop.
   
   [source, clojure]
  
positive.code: 
  We can use this to express the concept of doubling the result of an operation rather than having to write functions that perform specific doubled operations individually.
  
  == Anonymous Functions
  
  An anonymous function is a function without a name.
  In Clojure these can be defined in two ways, `fn` and the literal `#(...)`.
  
negative.code: ----
  
  The returned function form `adder` is a closure.
  This means, it can access all of the variables that were in scope when the function was created.
  `add-five` has access to `x` even though it is outside of the `adder` function definition.
  
  === Filter
  