perl -lane "push @{$H{$F[0]}},$F[1]}{print map{$_,qq( ---> ),scalar @{$H{$_}},$/,(join $/,@{$H{$_}}),$/,$/}keys %H" data1.txt

0011 ---> 2
Sally
Roy

1122 ---> 2
Brandon
Simson

2233 ---> 1
George

##</code><code>##

perl -MO=Deparse -lane "push @{$H{$F[0]}},$F[1]}{print map{ $_,qq( ---> ),scalar @{$H{$_}},$/,(join $/,@{$H{$_}}),$/,$/  }keys %H" 

BEGIN { $/ = "\n"; $\ = "\n"; }
LINE: while (defined($_ = readline ARGV)) {
    chomp $_;
    our @F = split(' ', $_, 0);
    push @{$H{$F[0]};}, $F[1];
}
{
    print map({$_, ' ---> ', scalar @{$H{$_};}, $/, join($/, @{$H{$_};}), $/, $/;} keys %H);
}
-e syntax OK

##</code><code>##


perl -MO=Deparse -l -e 1 
BEGIN { $/ = "\n"; $\ = "\n"; }
'???';
-e syntax OK

perl -MO=Deparse -a -e 1

LINE: while (defined($_ = readline ARGV)) {
    our @F = split(' ', $_, 0);
    '???';
}
-e syntax OK

perl -MO=Deparse -n -e 1

LINE: while (defined($_ = readline ARGV)) {
    '???';
}
-e syntax OK

perl -MO=Deparse -p -e 1

LINE: while (defined($_ = readline ARGV)) {
    '???';
}
continue {
    die "-p destination: $!\n" unless print $_;
}
-e syntax OK