The variables process functions also allow you to define additional variables in your theme.
To create a new variable, you must declare the function in the template. php file.
In order for your theme to have its preprocessors recognized, the template associated with the hook must exist inside the theme.
If the template does not exist in your theme, copy (or create) one and place it in the theme directory.
The syntax is the same as that just used for intercepting and overriding a variable, as seen above.