Function switch_channel_expand_variables_check

pub unsafe extern "C" fn switch_channel_expand_variables_check(
    channel: *mut switch_channel_t,
    in_: *const c_char,
    var_list: *mut switch_event_t,
    api_list: *mut switch_event_t,
    recur: u32,
) -> *mut c_char

\brief Expand varaibles in a string based on the variables in a paticular channel \param channel channel to expand the variables from \param in the original string \return the original string if no expansion takes place otherwise a new string that must be freed \note it’s necessary to test if the return val is the same as the input and free the string if it is not.