def is_datetime64_ns_dtype(arr_or_dtype):
if arr_or_dtype is None:<EOL><INDENT>return False<EOL><DEDENT>try:<EOL><INDENT>tipo = _get_dtype(arr_or_dtype)<EOL><DEDENT>except TypeError:<EOL><INDENT>if is_datetime64tz_dtype(arr_or_dtype):<EOL><INDENT>tipo = _get_dtype(arr_or_dtype.dtype)<EOL><DEDENT>else:<EOL><INDENT>return False<EOL><DEDENT><DEDENT>return tipo == _NS_DTYPE or getattr(tipo, '<STR_LIT>', None) == _NS_DTYPE<EOL>
Check whether the provided array or dtype is of the datetime64[ns] dtype.

Parameters
----------
arr_or_dtype : array-like
    The array or dtype to check.

Returns
-------
boolean
    Whether or not the array or dtype is of the datetime64[ns] dtype.

Examples
--------
>>> is_datetime64_ns_dtype(str)
False
>>> is_datetime64_ns_dtype(int)
False
>>> is_datetime64_ns_dtype(np.datetime64)  # no unit
False
>>> is_datetime64_ns_dtype(DatetimeTZDtype("ns", "US/Eastern"))
True
>>> is_datetime64_ns_dtype(np.array(['a', 'b']))
False
>>> is_datetime64_ns_dtype(np.array([1, 2]))
False
>>> is_datetime64_ns_dtype(np.array([], dtype=np.datetime64))  # no unit
False
>>> is_datetime64_ns_dtype(np.array([],
                           dtype="datetime64[ps]"))  # wrong unit
False
>>> is_datetime64_ns_dtype(pd.DatetimeIndex([1, 2, 3],
                           dtype=np.datetime64))  # has 'ns' unit
True