Thy_Info.dependencies: ignore already loaded theories, according to initial prover session status;
/* Title: Pure/Thy/thy_load.scala
Author: Makarius
Loading files that contribute to a theory.
*/
package isabelle
abstract class Thy_Load
{
def is_loaded(name: String): Boolean
def check_thy(dir: Path, name: String): (String, Thy_Header.Header)
}