       [a: 1, c: 3, a: 5]
 
   """
+  @spec take(t, [key]) :: t
   def take(keywords, keys) when is_list(keywords) do
     :lists.filter(fn {k, _} -> k in keys end, keywords)
   end

      [a: 1]

  """
  def to_list(keyword) when is_list(keyword) do
    keyword
  end

      [a: 1, c: 3, a: 5]

  """
  @spec drop(t, [key]) :: t
  def drop(keywords, keys) when is_list(keywords) do
    :lists.filter(fn {k, _} -> not k in keys end, keywords)
  end
