code: def get_key_filename(vm_):
      '''
      Check SSH private key file and return absolute path if exists.
      '''
      key_filename = config.get_cloud_config_value(
          'ssh_private_key', vm_, __opts__, search_global=False, default=None
      )
      if key_filename is not None:
          key_filename = os.path.expanduser(key_filename)
          if not os.path.isfile(key_filename):
              raise SaltCloudConfigError(
                  'The defined ssh_private_key \'{0}\' does not exist'.format(
                      key_filename
                  )
              )
  
          return key_filenamf get_key_filename(vm_):
      '''
      Check SSH private key file and return absolute path if exists.
      '''
      key_filename = config.get_cloud_config_value(
          'ssh_private_key', vm_, __opts__, search_global=False, default=None
      )
      if key_filename is not None:
          key_filename = os.path.expanduser(key_filename)
          if not os.path.isfile(key_filename):
              raise SaltCloudConfigError(
                  'The defined ssh_private_key \'{0}\' does not exist'.format(
                      key_filename
                  )
              )
  
          return key_filename
docs: Check SSH private key file and return absolute path if exists.