write the json representation of value v into the file file. Only bool, string, numeric, map, tab and their nestings can be translated into Json, cf. sect. Defining a value in Json format

See also Data Exchange Functions: @dump    @dumpvar    @gnuplot    @json_read    @json_string    @json_write    @loadvalue    @loadvar    @nim2vezer    @parse    @plot    @read_file    @rplot    @savevalue    @set_osc_handling_double    @set_osc_handling_int64    @set_osc_handling_tab    @string2fun    @string2obj    @string2proc    @to_num    @xml_read    @xml_string