@spec expired?(any()) :: boolean()

@spec extract_header([{binary(), binary()}] | map(), binary()) :: binary() | nil

@spec generate_expiration_timestamp(any()) :: DateTime.t()

@spec generate_info({:ok, Req.Response.t()} | nil, binary()) ::
  %FindSiteIcon.IconInfo{
    expiration_timestamp: term(),
    size: term(),
    url: term()
  }
  | nil

@spec generate_size(any()) :: integer() | nil

@spec icon_info_for(
  binary() | nil,
  keyword()
) ::
  %FindSiteIcon.IconInfo{
    expiration_timestamp: term(),
    size: term(),
    url: term()
  }
  | nil

@spec reject_bad_content_type(any()) :: nil | {:ok, Req.Response.t()}

@spec unexpired?(any()) :: boolean()