pub unsafe extern "C" fn rocksdb_mergeoperator_create(
state: *mut c_void,
destructor: Option<unsafe extern "C" fn(state: *mut c_void)>,
full_merge: Option<unsafe extern "C" fn(state: *mut c_void, destructor: *const c_char, full_merge: usize, partial_merge: *const c_char, delete_value: usize, name: *const *const c_char, arg1: *const usize, arg2: c_int, arg3: *mut c_uchar, arg4: *mut usize) -> *mut c_char>,
partial_merge: Option<unsafe extern "C" fn(state: *mut c_void, destructor: *const c_char, full_merge: usize, partial_merge: *const *const c_char, delete_value: *const usize, name: c_int, arg1: *mut c_uchar, arg2: *mut usize) -> *mut c_char>,
delete_value: Option<unsafe extern "C" fn(state: *mut c_void, destructor: *const c_char, full_merge: usize)>,
name: Option<unsafe extern "C" fn(state: *mut c_void) -> *const c_char>
) -> *mut rocksdb_mergeoperator_t