is a variable defined in `
Its value is
- This variable may be risky if used as a file-local variable.
Themes that are considered safe to load.
If the value is a list, each element should be either the SHA-256
hash of a safe theme file, or the symbol `default', which stands
for any theme in the built-in Emacs theme directory (a directory
named "themes" in `data-directory').
If the value is t, Emacs treats all themes as safe.
This variable cannot be set in a Custom theme.
You can customize this variable.
This variable was introduced, or its default value was changed, in
version 24.1 of Emacs.