@callback encode(
  SPARQL.Query.Result.t(),
  keyword()
) :: keyword(String.t())

Encodes a SPARQL.Query.Result.

It returns an {:ok, string} tuple, with string being the serialized SPARQL.Query.Result, or {:error, reason} if an error occurs.

@callback encode!(
  SPARQL.Query.Result.t(),
  keyword()
) :: String.t()

Encodes a SPARQL.Query.Result.

As opposed to encode, it raises an exception if an error occurs.

Note: The __using__ macro automatically provides an overridable default implementation based on the non-bang encode function.