Update Strings.php

Author: Roman Lakhtadyr

src/Nerd/Common/Strings.php

@@ -15,11 +15,3 @@ function indent($length, $text)
     }, $text);
     return implode(PHP_EOL, $result);
 }
-
-function toHeadTail($string)
-{
-    if (strlen($string) == 0) {
-        return [null, null];
-    }
-    return [$string[0], substr($string, 1)];
-}