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