def merge(directory=None, revisions='', message=None, branch_label=None,
          rev_id=None):
    """Merge two revisions together.  Creates a new migration file"""
    config = current_app.extensions['migrate'].migrate.get_config(directory)
    command.merge(config, revisions, message=message,
                  branch_label=branch_label, rev_id=rev_id)
Merge two revisions together.  Creates a new migration file
src/flask_migrate/__init__.py