code: def is_datetime64_ns_dtype(arr_or_dtype):
      
  
      if arr_or_dtype is None:
          return False
      try:
          tipo = _get_dtype(arr_or_dtype)
      except TypeError:
          if is_datetime64tz_dtype(arr_or_dtype):
              tipo = _get_dtype(arr_or_dtype.dtype)
          else:
              return False
      return tipo == _NS_DTYPE or getattr(tipo, 'base', None) == _NS_DTYPE
docs: 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