def METHOD_NAME(self):
    # This needs to set a self.field_list that contains all the available,
    # on-disk fields. No derived fields should be defined here.
    # NOTE: Each should be a tuple, where the first element is the on-disk
    # fluid type or particle type.  Convention suggests that the on-disk
    # fluid type is usually the dataset_type and the on-disk particle type
    # (for a single population of particles) is "io".
    pass