$ cat /tmp/countries
Russia  8650    262     Asia
Canada  3852    24      North America
China   3692    866     Asia
USA     3615    219     North America
Brazil  3286    116     South America
Australia       2968    14      Australia
India   1269    637     Asia
Argentina       1072    26      South America
Sudan   968     19      Africa
Algeria 920     18      Africa

# Still prints column 3, but it is supposed to be gone because of NF = 2.
$ target/debug/frawk -F "\t" '{ NF=2; print $3, $1;  }' /tmp/countries
with_bytes 2
262 Russia
24 Canada
866 China
219 USA
116 Brazil
14 Australia
637 India
26 Argentina
19 Sudan
18 Algeria

$ gawk -F "\t" '{ NF=2; print $3, $1;  }' /tmp/countries
 Russia
 Canada
 China
 USA
 Brazil
 Australia
 India
 Argentina
 Sudan
 Algeria

$ mawk -F "\t" '{ NF=2; print $3, $1;  }' /tmp/countries
 Russia
 Canada
 China
 USA
 Brazil
 Australia
 India
 Argentina
 Sudan
 Algeria