code: def get_namespace_prefix(self, package=None):
          
          result = ""
          if package is None:
              package = self.project_config.project__package__name_managed
          packages = self.tooling.query(
              "SELECT SubscriberPackage.NamespacePrefix, SubscriberPackage.Name "
              "FROM InstalledSubscriberPackage"
          )
          match = [
              p for p in packages["records"] if p["SubscriberPackage"]["Name"] == package
          ]
          if match:
              result = match[0]["SubscriberPackage"]["NamespacePrefix"] + "__"
          return result
docs: Returns the namespace prefix (including __) for the specified package name.
          (Defaults to project__package__name_managed from the current project config.)
  
          Returns an empty string if the package is not installed as a managed package.