If any part of LIST is an array, "foreach" will get very confused if
       you add or remove elements within the loop body, for example with
       "splice".   So don’t do that.

##</code><code>##

  @foo = map { 'd' eq $_ ? ($_,'h') : $_ } @foo;
  # puts 'h' right after 'd'

##</code><code>##

my @extras;
foreach my $x (@foo) {
  push @extras, 'h' if $x eq 'd';
  print $x;
}
push @foo, @extras;
# didn't print 'h'.  But if we add:
print foreach @extras;
# that works ... but duplicates code.

##</code><code>##

{
  my @extras;
  foreach my $x (@foo) {
    push @extras, 'h' if $x eq 'd';
  }
  push @foo, @extras;
}
foreach my $x (@foo)
{
  print $x;
}