my $x = "";
$x=~s/(.{0,3})/"'$1".(' 'x(3-length($1)))."'\n"/eg;
print $x
---
'   '


my $x = "1234567890";
$x=~s/(.{0,3})/"'$1".(' 'x(3-length($1)))."'\n"/eg;
print $x
---
'123'
'456'
'789'
'0  '
'   '

##</code><code>##

my $x = "";
$x=~s/(.{1,3})/"'$1".(' 'x(3-length($1)))."'\n"/eg;
print $x
---
___prints_nothing___


my $x = "1234567890";
$x=~s/(.{1,3})/"'$1".(' 'x(3-length($1)))."'\n"/eg;
print $x
---
'123'
'456'
'789'
'0  '