code: def _concat_datetimetz(to_concat, name=None):
      """
      concat DatetimeIndex with the same tz
      all inputs must be DatetimeIndex
      it is used in DatetimeIndex.append also
      """
      # Right now, internals will pass a List[DatetimeArray] here
      # for reductions like quantile. I would like to disentangle
      # all this before we get here.
      sample = to_concat[0]
  
      if isinstance(sample, ABCIndexClass):
          return sample._concat_same_dtype(to_concat, name=name)
      elif isinstance(sample, ABCDatetimeArray):
          return sample._concat_same_type(to_concat)
  
file_path: catboost/contrib/python/pandas/py2/pandas/core/dtypes/concat.py
imports: import numpy
  from pandas._libs import tslib, tslibs
  from pandas.core.dtypes.common import _NS_DTYPE, _TD_DTYPE, is_bool_dtype, is_categorical_dtype, is_datetime64_dtype, is_datetime64tz_dtype, is_dtype_equal, is_extension_array_dtype, is_object_dtype, is_sparse, is_timedelta64_dtype
  from pandas.core.dtypes.generic import ABCDatetimeArray, ABCDatetimeIndex, ABCIndexClass, ABCPeriodIndex, ABCRangeIndex, ABCSparseDataFrame, ABCTimedeltaIndex
  from pandas import compat
label_desc: Use image node_id 10 for calling a global function with example usage: _concat_datetimetz(to_concat, name) and returns: sample, sample