def _concat_datetimetz(to_concat, name=None):
<EOL>sample = to_concat[<NUM_LIT:0>]<EOL>if isinstance(sample, ABCIndexClass):<EOL><INDENT>return sample._concat_same_dtype(to_concat, name=name)<EOL><DEDENT>elif isinstance(sample, ABCDatetimeArray):<EOL><INDENT>return sample._concat_same_type(to_concat)<EOL><DEDENT>
concat DatetimeIndex with the same tz
all inputs must be DatetimeIndex
it is used in DatetimeIndex.append also