       ** (Enum.OutOfBoundsError) out of bounds error
 
   """
-  @spec fetch!(t, integer) :: element | no_return
+  @spec fetch!(t, index) :: element | no_return
   def fetch!(enumerable, index) do
     case fetch(enumerable, index) do
       {:ok, h} -> h

      :error

  """
  @spec fetch(t, integer) :: {:ok, element} | :error
  def fetch(enumerable, index)
  def fetch(first..last, index) when is_integer(index),
    do: fetch_range(first, last, index)

      :none

  """
  @spec at(t, index, default) :: element | default
  def at(enumerable, index, default \\ nil) do
    case fetch(enumerable, index) do
      {:ok, h} -> h
