pub unsafe extern "C" fn crocksdb_mergeoperator_create(
state: *mut c_void,
destroy: extern "C" fn(_: *mut c_void),
full_merge: extern "C" fn(arg: *mut c_void, key: *const c_char, key_len: size_t, existing_value: *const c_char, existing_value_len: size_t, operands_list: *const *const c_char, operands_list_len: *const size_t, num_operands: c_int, success: *mut u8, new_value_length: *mut size_t) -> *const c_char,
partial_merge: extern "C" fn(arg: *mut c_void, key: *const c_char, key_len: size_t, operands_list: *const *const c_char, operands_list_len: *const size_t, num_operands: c_int, success: *mut u8, new_value_length: *mut size_t) -> *const c_char,
delete_value: Option<extern "C" fn(_: *mut c_void, value: *const c_char, value_len: *mut size_t)>,
name_fn: extern "C" fn(_: *mut c_void) -> *const c_char
) -> *mut DBMergeOperator