Function unqlite_sys::unqlite_create_function

pub unsafe extern "C" fn unqlite_create_function(
    pVm: *mut unqlite_vm, 
    zName: *const c_char, 
    xFunc: Option<unsafe extern "C" fn(_: *mut unqlite_context, _: c_int, _: *mut *mut unqlite_value) -> c_int>, 
    pUserData: *mut c_void
) -> c_int