switch($argon) {
my $case = 0; {$IMPUTEinfile="$ARGV[$i]";}
my $case = 1; {$outfilePRE="$ARGV[$i]";}
else {
    help();
}
}

##</code><code>##

if    ($argon == 0) { $IMPUTEinfile = "$ARGV[$i]"; }
elsif ($argon == 1) { $outfilePRE   = "$ARGV[$i]"; }
else  { help(); }