# Example usage:
awk 'FNR==NR{a[$1]=$2; next}; {if($9 in a) {print $0, "\t"a[$9];} else {print $0, "\tNA"}}' input_file_1 input_file_2
# This command does a VLOOKUP-type operation between two files using
#	awk. With the numbers above, column 1 from input_file_1 is used 
#	an a key in an array with column 2 of input_file_1 as the match for 
#	the key. Column 9 of input_file_2 is then compared to the keys from
#	input_file_1 and any matches return the associated match from 
#	input_file_1 (here, column 2).

private static long factorial(int n){  
	if (n == 1)
    	return 1;    
    else
		return n * factorial(n-1);
        }

>>> def sum_digits(n):
        """Return the sum of the digits of positive integer n."""
        if n < 10:
            return n
        else:
            all_but_last, last = n // 10, n % 10
            return sum_digits(all_but_last) + last

void recurse()
{
    ... .. ...
    recurse();
    ... .. ...
}

int main()
{
    ... .. ...
    recurse();
    ... .. ...
}