code: public This getGlobal(final Interpreter declaringInterpreter) {
          if (this.parent != null)
              return this.parent.getGlobal(declaringInterpreter);
          else
              return this.getThis(declaringInterpreter);
      }
docs: Get the top level namespace or this namespace if we are the top. Note:
  this method should probably return type bsh.This to be consistent with
  getThis();
  @param declaringInterpreter the declaring interpreter
  @return the global