+ /christmas(?:[-_ ]?(?:tree|time|eve|pudding))?/
+
+
+ATTENTION:
+
+It is absolutely important, that you use grouping
+parentheses instead of capturing parentheses!!
+
+Grouping parentheses are:
+
+ (?: )
+
+If you use capturing parentheses, which are
+
+ ( )
+
+it will produce errors and the regex won't work and
+at least your targets will not get collapsed.
+