How to use the h5netcdf.compat.unicode function in h5netcdf

def createVariable(self, varname, datatype, dimensions=(), zlib=False,
                       complevel=4, shuffle=True, fletcher32=False,
                       chunksizes=None, fill_value=None):
        if len(dimensions) == 0:  # it's a scalar
            # rip off chunk and filter options for consistency with netCDF4-python

            chunksizes = None
            zlib = False
            fletcher32 = False
            shuffle = False

        if datatype is str:
            datatype = h5py.special_dtype(vlen=unicode)

        kwds = {}
        if zlib:
            # only add compression related keyword arguments if relevant (h5py
            # chokes otherwise)
            kwds['compression'] = 'gzip'
            kwds['compression_opts'] = complevel
            kwds['shuffle'] = shuffle

        return super(Group, self).create_variable(
            varname, dimensions, dtype=datatype, fletcher32=fletcher32,
            chunks=chunksizes, fillvalue=fill_value, **kwds)

def dtype(self):
        dt = self._h5ds.dtype
        if h5py.check_dtype(vlen=dt) is unicode:
            return str
        return dt