* in-place empty_ for Batch
* change Batch.empty to in-place fill; add copy option for Batch construction
* type signiture & remove shadow names for copy
* add doc for data type (only support numbers and object data type)
* add unit test for Batch copy
* fix pep8
* add test case for Batch.empty
* doc fix
* fix pep8
* use object to test Batch
* test commit
* refact
* change Batch(copy) testcase
* minor fix
Co-authored-by: Trinkle23897 <463003665@qq.com>