int format_graphite (char *buffer,
size_t buffer_size, const data_set_t *ds,
const value_list_t *vl, const char *prefix,
const char *postfix, const char escape_char,
int format_graphite (char *buffer,
size_t buffer_size, const data_set_t *ds,
const value_list_t *vl, const char *prefix,
const char *postfix, const char escape_char,