Function get_variable

pub unsafe fn get_variable<'a>(
    callback: retro_environment_t,
    key: &'a str,
) -> Option<&'a str>

Interface to acquire user-defined information from environment that cannot feasibly be supported in a multi-system way.

The key should be set to a key which has already been set by set_variables or set_core_options.

Returns None if the variable could not be found.