- head => sub { $_[0] . '%' },
- tail => sub { '%' . $_[0] },
- substr => sub { '%' . $_[0] . '%' },
+ head => sub { trim($_[0]) . '%' },
+ tail => sub { '%' . trim($_[0]) },
+ substr => sub { '%' . trim($_[0]) . '%' },
+ trim => sub { trim($_[0]) },