RDF.Quad.valid-question-mark

You're seeing just the function valid-question-mark, go back to RDF.Quad module for more information.

Specs

valid?(t() | any()) :: boolean()

Checks if the given tuple is a valid RDF quad.

The elements of a valid RDF quad must be RDF terms. On the subject position only IRIs and blank nodes allowed, while on the predicate and graph name position only IRIs allowed. The object position can be any RDF term.