filterx: flatten()

[alltilla]

Example:

dict = json({"top_level_field":42,"top_level_dict":{"inner_field":1337,"inner_dict":{"inner_inner_field":1}}});

flat_with_default_separator = dict;
flatten(flat_with_default_separator);
# {"top_level_field":42,"top_level_dict.inner_dict.inner_inner_field":1,"top_level_dict.inner_field":1337},

flat_with_custom_separator = dict;
flatten(flat_with_custom_separator, separator="->");
# {"top_level_field":42,"top_level_dict->inner_dict->inner_inner_field":1,"top_level_dict->inner_field":1337}