def cat(self, *others, sep: str | bytes | Any = "") -> T_DataArray:
        """
        Concatenate strings elementwise in the DataArray with other strings.

        The other strings can either be string scalars or other array-like.
        Dimensions are automatically broadcast together.

        An optional separator `sep` can also be specified. If `sep` is
        array-like, it is broadcast against the array and applied elementwise.

        Parameters
        ----------
        *others : str or array-like of str
            Strings or array-like of strings to concatenate elementwise with
            the current DataArray.
        sep : str or array-like of str, default: "".
            Separator to use between strings.
            It is broadcast in the same way as the other input strings.
            If array-like, its dimensions will be placed at the end of the output array dimensions.

        Returns
        -------
        concatenated : same type as values

        Examples
        --------
        Create a string array

        >>> myarray = xr.DataArray(
        ...     ["11111", "4"],
        ...     dims=["X"],
        ... )

        Create some arrays to concatenate with it

        >>> values_1 = xr.DataArray(
        ...     ["a", "bb", "cccc"],
        ...     dims=["Y"],
        ... )
        >>> values_2 = np.array(3.4)
        >>> values_3 = ""
        >>> values_4 = np.array("test", dtype=np.str_)

        Determine the separator to use

        >>> seps = xr.DataArray(
        ...     [" ", ", "],
        ...     dims=["ZZ"],
        ... )

        Concatenate the arrays using the separator

        >>> myarray.str.cat(values_1, values_2, values_3, values_4, sep=seps)
        <xarray.DataArray (X: 2, Y: 3, ZZ: 2)> Size: 1kB
        array([[['11111 a 3.4  test', '11111, a, 3.4, , test'],
                ['11111 bb 3.4  test', '11111, bb, 3.4, , test'],
                ['11111 cccc 3.4  test', '11111, cccc, 3.4, , test']],
        <BLANKLINE>
               [['4 a 3.4  test', '4, a, 3.4, , test'],
                ['4 bb 3.4  test', '4, bb, 3.4, , test'],
                ['4 cccc 3.4  test', '4, cccc, 3.4, , test']]], dtype='<U24')
        Dimensions without coordinates: X, Y, ZZ

        See Also
        --------
        pandas.Series.str.cat
        str.join
        """
        sep = self._stringify(sep)
        others = tuple(self._stringify(x) for x in others)
        others = others + (sep,)

        # sep will go at the end of the input arguments.
        func = lambda *x: x[-1].join(x[:-1])

        return self._apply(
            func=func,
            func_args=others,
            dtype=self._obj.dtype.kind,
        )

        Concatenate strings elementwise in the DataArray with other strings.

        The other strings can either be string scalars or other array-like.
        Dimensions are automatically broadcast together.

        An optional separator `sep` can also be specified. If `sep` is
        array-like, it is broadcast against the array and applied elementwise.

        Parameters
        ----------
        *others : str or array-like of str
            Strings or array-like of strings to concatenate elementwise with
            the current DataArray.
        sep : str or array-like of str, default: "".
            Separator to use between strings.
            It is broadcast in the same way as the other input strings.
            If array-like, its dimensions will be placed at the end of the output array dimensions.

        Returns
        -------
        concatenated : same type as values

        Examples
        --------
        Create a string array

        >>> myarray = xr.DataArray(
        ...     ["11111", "4"],
        ...     dims=["X"],
        ... )

        Create some arrays to concatenate with it

        >>> values_1 = xr.DataArray(
        ...     ["a", "bb", "cccc"],
        ...     dims=["Y"],
        ... )
        >>> values_2 = np.array(3.4)
        >>> values_3 = ""
        >>> values_4 = np.array("test", dtype=np.str_)

        Determine the separator to use

        >>> seps = xr.DataArray(
        ...     [" ", ", "],
        ...     dims=["ZZ"],
        ... )

        Concatenate the arrays using the separator

        >>> myarray.str.cat(values_1, values_2, values_3, values_4, sep=seps)
        <xarray.DataArray (X: 2, Y: 3, ZZ: 2)> Size: 1kB
        array([[['11111 a 3.4  test', '11111, a, 3.4, , test'],
                ['11111 bb 3.4  test', '11111, bb, 3.4, , test'],
                ['11111 cccc 3.4  test', '11111, cccc, 3.4, , test']],
        <BLANKLINE>
               [['4 a 3.4  test', '4, a, 3.4, , test'],
                ['4 bb 3.4  test', '4, bb, 3.4, , test'],
                ['4 cccc 3.4  test', '4, cccc, 3.4, , test']]], dtype='<U24')
        Dimensions without coordinates: X, Y, ZZ

        See Also
        --------
        pandas.Series.str.cat
        str.join
        
xarray/core/accessor_str.py