       iex> 1 / 2
       0.5
 
-      iex> 2 / 1
-      2.0
+      iex> -3.0 / 2.0
+      -1.5
+
+      iex> 5 / 1
+      5.0
 
   """
   @spec (number / number) :: float


      iex> round(5.6)
      6
      iex> round(5.2)
      5
      iex> round(-9.9)
      -10

  """
  @spec round(float) :: integer

  end

  @doc """
  Returns the head of a list. Raises `ArgumentError` if the list is empty.

  Allowed in guard tests. Inlined by the compiler.

