code: public Dep newDep(Term from, Term to, String rfunc) {
      Dep newDep = new Dep(from, to, rfunc);
      annotationContainer.add(newDep, Layer.DEPS, AnnotationType.DEP);
      return newDep;
  }
docs: Creates a new dependency. The Dep is added to the document object.
  @param from the origin term of the dependency.
  @param to the target term of the dependency.
  @param rfunc relational function of the dependency.
  @return a new dependency.