 
   """
   @spec keyfind([tuple], any, non_neg_integer, any) :: any
-  def keyfind(list, key, position, default \\ nil) do
+  def keyfind(list, key, position, default \\ nil) when is_integer(position) do
     :lists.keyfind(key, position + 1, list) || default
   end
 


  """
  @spec keymember?([tuple], any, non_neg_integer) :: boolean
  def keymember?(list, key, position) do
    :lists.keymember(key, position + 1, list)
  end



  """
  @spec keystore([tuple], any, non_neg_integer, tuple) :: [tuple, ...]
  def keystore(list, key, position, new_tuple) when is_integer(position) do
    :lists.keystore(key, position + 1, list, new_tuple)
  end

