NULL if both arguments option and value are provided.
The currently set value if the argument value is missing.
All set options if the argument option is missing.
Arguments
option
any options can be defined, using 'key, value' pairs.
If 'value' is missing the current set value is returned for the given 'option'.
If both are missing. all set options are returned.
value
the corresponding value to set for the given option.
update_python_defaults
a logical (default is FALSE) controling if the corresponding
stanza variables should also updated in Python.