docs: def auth_plugins(auth_plugins=None):
      """Authentication plugins.
  
      Usage, Add any plugin here that will serve as a rapid means to
      authenticate to an OpenStack environment.
  
      Syntax is as follows:
      >>> __auth_plugins__ = {
      ...     'new_plugin_name': {
      ...         'os_auth_url': 'https://localhost:5000/v2.0/tokens',
      ...         'os_prefix': {
      ...             'os_apikey': 'apiKeyCredentials',
      ...             'os_password': 'passwordCredentials'
      ...         },
      ...         'args': {
      ...             'commands': [
      ...                 '--new-plugin-name-auth'
      ...             ],
      ...             'choices': [
      ...                 'RegionOne'
      ...             ],
      ...             'help': 'Authentication plugin for New Plugin Name',
      ...             'default': os.environ.get('OS_NEW_PLUGIN_AUTH', None),
      ...             'metavar': '[REGION]'
      ...         }
      ...     }
      ... }
  
      If the subdomain is in the auth url, as is the case with hp, add
      "%(region)s" to the "os_auth_url" value. The region value from the list of
      choices will be used as the string replacement. Note that if the
      `os_prefix` key is added the system will override the authentication body
      prefix with the string provided. At this time the choices are os_apikey,
      os_password, os_token. All key entries are optional and should one not be
      specified with a credential type a `NotImplementedError` will be raised.
  
      :param auth_plugins: Additional plugins to add in
      :type auth_plugins: ``dict``
      :returns: ``dict``
      """
  
      __auth_plugins__ = {
          'os_rax_auth': {
              'os_auth_url': 'https://identity.api.rackspacecloud.com/v2.0/'
                             'tokens',
              'os_prefix': {
                  'os_apikey': 'RAX-KSKEY:apiKeyCredentials',
                  'os_password': 'passwordCredentials'
              },
              'args': {
                  'commands': [
                      '--os-rax-auth'
                  ],
                  'choices': [
                      'dfw',
                      'ord',
                      'iad',
                      'syd',
                      'hkg',
                      'lon'
                  ],
                  'help': 'Authentication Plugin for Rackspace Cloud'
                          ' env[OS_RAX_AUTH]',
                  'default': os.environ.get('OS_RAX_AUTH', None),
                  'metavar': '[REGION]'
              }
          },
          'rax_auth_v1': {
              'os_auth_version': 'v1.0',
              'os_auth_url': 'https://identity.api.rackspacecloud.com/v1.0',
              'args': {
                  'commands': [
                      '--rax-auth-v1'
                  ],
                  'action': 'store_true',
                  'help': 'Authentication Plugin for Rackspace Cloud V1'
              }
          },
          'os_rax_auth_lon': {
              'os_auth_url': 'https://lon.identity.api.rackspacecloud.com/'
                             'v2.0/tokens',
              'os_prefix': {
                  'os_apikey': 'RAX-KSKEY:apiKeyCredentials',
                  'os_password': 'passwordCredentials'
              },
              'args': {
                  'commands': [
                      '--os-rax-auth-lon'
                  ],
                  'choices': [
                      'lon'
                  ],
                  'help': 'Authentication Plugin for Rackspace Cloud'
                          ' env[OS_RAX_AUTH_LON]',
                  'default': os.environ.get('OS_RAX_AUTH_LON', None),
                  'metavar': '[REGION]'
              }
          },
          'os_hp_auth': {
              'os_auth_url': 'https://%(region)s.identity.hpcloudsvc.com:35357/'
                             'v2.0/tokens',
              'os_prefix': {
                  'os_password': 'passwordCredentials'
              },
              'args': {
                  'commands': [
                      '--os-hp-auth'
                  ],
                  'choices': [
                      'region-b.geo-1',
                      'region-a.geo-1'
                  ],
                  'help': 'Authentication Plugin for HP Cloud'
                          ' env[OS_HP_AUTH]',
                  'default': os.environ.get('OS_HP_AUTH', None),
                  'metavar': '[REGION]'
              }
          }
      }
      if auth_plugins:
          __auth_plugins__.update(auth_plugins)
  
      return __auth_plugins__