code: def heads(directory=None, verbose=False, resolve_dependencies=False):
      
      if alembic_version >= (0, 7, 0):
          config = current_app.extensions['migrate'].migrate.get_config(
              directory)
          command.heads(config, verbose=verbose,
                        resolve_dependencies=resolve_dependencies)
      else:
          raise RuntimeError('Alembic 0.7.0 or greater is required')
docs: Show current available heads in the script directory