Style stuff:

• Indent two spaces, not 4.
• Conventionally, use head() / head_key() over reset() + each(). They have simpler semantics.
• Avoid redundant empty() on defined variables. if (empty($x)) is always equivalent to if (!$x) for defined $x.
• Prefer {$variable} in strings over $variable.
• For printf() style methods, prefer %s over {$variable} in a string. For example, if we eventually introduce a source called **stars**, it will render incorrectly (with a bold style) if embedded in the string directly.