default_format
static const char default_format[] = { "%n\t%E\t%x\n" };
const char *format = default_format;
if (format != default_format)
fmt = default_format;
char default_format[] = { "%g" }; /* default */
default_format(node, buf, len);
default_format(node, buf, len);
default_format(node, buf, len);
{ NULL, default_format }