def get_default_roles():
    """Returns:
    default roles (list): default role definitions as dictionaries:
      {
        'name': role name,
        'description': role description,
        'scopes': list of scopes,
      }
    """
    default_roles = [
        {
            'name': 'user',
            'description': 'Standard user privileges',
            'scopes': [
                'self',
            ],
        },
        {
            'name': 'admin',
            'description': 'Elevated privileges (can do anything)',
            'scopes': [
                'admin-ui',
                'admin:users',
                'admin:servers',
                'admin:services',
                'tokens',
                'admin:groups',
                'list:services',
                'read:services',
                'read:hub',
                'proxy',
                'shutdown',
                'access:services',
                'access:servers',
                'read:roles',
                'read:metrics',
                'shares',
            ],
        },
        {
            'name': 'server',
            'description': 'Post activity only',
            'scopes': [
                'users:activity!user',
                'access:servers!server',
            ],
        },
        {
            'name': 'token',
            'description': 'Token with same permissions as its owner',
            'scopes': ['inherit'],
        },
    ]
    return default_roles
Returns:
default roles (list): default role definitions as dictionaries:
{
'name': role name,
'description': role description,
'scopes': list of scopes,
}
jupyterhub/roles.py