FilterPanelAPI          Class to encapsulate the API of the filter
                        panel of a teal app
filter_state_api        Managing 'FilteredData' states
get_filter_expr         Gets filter expression for multiple 'datanames'
                        taking into account its order.
init_filtered_data      Initialize 'FilteredData'
teal_slice              Specify single filter
teal_slices             Complete filter specification
