Encapsulates state which is passed to other methods used in bulk loading.
It is optionally passed to import/export transform functions.
It is passed to connector objects.
Properties:
filename: The filename flag passed on the command line.
loader_opts: The loader_opts flag passed on the command line.
exporter_opts: The exporter_opts flag passed on the command line.
current_instance: The current entity or model instance.
current_entity: On export, the current entity instance.
current_dictionary: The current input or output dictionary.