Switches current theme to new template and stylesheet names.
Accepts one argument: $stylesheet of the theme. ($stylesheet is the name of your folder slug. It's the same value that you'd use for a child theme, something like `twentythirteen`.) It also accepts an additional function signature of two arguments: $template then $stylesheet. This is for backwards compatibility.
<?php switch_theme( $stylesheet ) ?>
Optional usage for backwards compatibility:
<?php switch_theme( $template, $stylesheet ) ?>
Altered 4/23 to define default/alternate function signature and parameters
switch_theme() is located in