DigitalOcean.Image.list

You're seeing just the function list, go back to DigitalOcean.Image module for more information.
Link to this function

list(opts \\ [])

Specs

Retrieve a list of images.

Example retrieving all images

iex> DigitalOcean.Image.list() |> DigitalOcean.request()
{ :ok, %DigitalOcean.Response{} }

Example retrieving distribution images

iex> DigitalOcean.Image.list(type: "distribution") |> DigitalOcean.request()
{ :ok, %DigitalOcean.Response{} }

See the official DigitalOcean v2 API documentation for all options listing images.