github.com/benhoyt/goawk@v1.8.1/testdata/t.array1 (about)

     1  {for(i=1; i<=NF; i++) {
     2  	if (x[$i] == "")
     3  		y[++n] = $i
     4  	x[$i]++
     5   }
     6  }
     7  END {
     8  	for (i=0; i<n; i++)
     9  		print (y[i], x[y[i]])
    10  }