######################
#     Directives     #
######################

use strict;
use warnings;

######################
#     Main Code      #
######################

sub expand_name; 

my @result = expand_name(@ARGV); 

my $i=0; # i,j,k,etc. are the traditional names for general purpose loop counters or iterators

foreach (@result)
	{
	if ($_)
		{
		print "$ARGV[$i] is $_\n";
		}
	else
		{
		print"Sorry bub. $ARGV[$i] is not an amino acid.\n";
		}
	$i++;
	}

######################
#    Subroutines     #
######################

sub expand_name 			
	{
	
	my $amino_acid;
	my @return_list;

	my %convert = (	"S" => "Ser",
			"F" => "Phe",
			"L" => "Leu",
			"Y" => "Tyr",
			"C" => "Cys",
			"W" => "Trp",
			"P" => "Pro",
			"H" => "His",
			"Q" => "Glu",
			"I" => "Iso",
			"M" => "Met",
			"T" => "Thr",
			"N" => "Asp",
			"K" => "Lys",
			"V" => "Val",
			"D" => "Asp",
			"E" => "Glu",
			"G" => "Gly",			
			"R" => "Arg", 
			"A" => "Ala" );
		
	foreach $amino_acid (@_)
		{
		push (@return_list, $convert{$amino_acid} )
		}
			
	@return_list; ## this returns the list that we are putting into @result above. 
	
	}