/// <summary>
 /// Unregisters an annotation schema with the registry.
 /// </summary>
 /// <param name="schema">The annotation schema to unregister.</param>
 public void Unregister(AnnotationSchema schema)
 {
     this.internalSchemas.Remove(schema);
 }
 /// <summary>
 /// Registers an annotation schema with the registry.
 /// </summary>
 /// <param name="schema">The annotation schema to register.</param>
 public void Register(AnnotationSchema schema)
 {
     this.internalSchemas.Add(schema);
 }