docs: def add_doc(self, doc):
          """ Simple dict of {'name': '@filename.pdf'}"""
          if isinstance(doc, HelloDoc) and doc.validate():
              self.docs.append(doc)
          else:
              if not doc.validate():
                  raise Exception("HelloDoc Errors %s" % (doc.errors,))
              else:
                  raise Exception("add_doc doc must be an instance of class HelloDoc")