Create a Series with both index and values equal to the index keys useful with map for returning an indexer based on an index
keep_tz : optional, defaults False.
return the data keeping the timezone.
If keep_tz is True:
If the timezone is not set, the resulting Series will have a datetime64[ns] dtype.
Otherwise the Series will have an datetime64[ns, tz] dtype; the tz will be preserved.
If keep_tz is False:
Series will have a datetime64[ns] dtype. TZ aware objects will have the tz removed.