   end
 
   @doc """
-  Gets the given attribute from a module. If the attribute
-  was marked with `accumulate` with `Module.register_attribute/3`,
-  a list is always returned.
+  Gets the given attribute from a module.
+
+  If the attribute was marked with `accumulate` with
+  `Module.register_attribute/3`, a list is always returned. `nil` is returned
+  if the attribute has not been marked with `accumulate` and has not been set
+  to any value.
 
   The `@` macro compiles to a call to this function. For example,
   the following code:

  end

  @doc """
  Attaches documentation to a given function or type. It expects
  the module the function/type belongs to, the line (a non negative
  integer), the kind (`def` or `defmacro`), a tuple representing
  the function and its arity, the function signature (the signature
  should be omitted for types) and the documentation, which should
  be either a binary or a boolean.


  @doc """
  Checks if the module defines a function or macro of the
  given `kind`.

  `kind` can be any of `:def`, `:defp`, `:defmacro` or `:defmacrop`.

  ## Examples

