 line breaks.
        parser : {{'lxml','etree'}}, default 'lxml'
            Parser module to use for building of tree. Only 'lxml' and
            'etree' are supported. With 'lxml', the ability to use XSLT
            stylesheet is supported.
        stylesheet : str, path object or file-like object, optional
            A URL, file-like object, or a raw string containing an XSLT
            script used to transform the raw XML output. Script should use
            layout of elements and attributes from original output. This
            argument requires ``lxml`` to be installed. Only XSLT 1.0
            scripts and not later versions is currently supported.
        {compression_options}

            .. versionchanged:: 1.4.0 Zstandard support.

        {storage_options}

        Returns
        -------
        None or str
            If ``io`` is None, returns the resulting XML format as a
            string. Otherwise returns None.

        See Also
        --------
        to_json : Convert the pandas object to a JSON string.
        to_html : Convert DataFrame to a html.

        Examples
        --------
        >>> df = pd.DataFrame({{'shape': ['square', 'circle', 'triangle'],
        ...                    'degrees': [360, 360, 180],
        ...                    'sides': [4, np.nan, 3]}})

        >>> df.to_xml()  # doctest: +SKIP
        <?xml version='1.0' encoding='utf-8'?>
        <data>
          <row>
            <index>0</index>
            <shape>square</shape>
            <degrees>360</degrees>
            <sides>4.0</sides>
          </row>
          <row>
            <index>1</index>
            <shape>circle</shape>
            <degrees>360</degrees>
            <sides/>
          </row>
          <row>
            <index>2</index>
            <shape>triangle</shape>
            <degrees>180</degrees>
            <sides>3.0</sides>
          </row>
        </data>

        >>> df.to_xml(attr_cols=[
        ...           'index', 'shape', 'degrees', 'sides'
        ...           ])  # doctest: +SKIP
        <?xml version='1.0' encoding='utf-8'?>
        <data>
          <row index="0" shape="square" degrees="360" sides="4.0"/>
          <row index="1" shape="circle" degrees="360"/>
          <row index="2" shape="triangle" degrees="180" sides="3.0"/>
        </data>

        >>> df.to_xml(namespaces={{"doc": "https://example.com"}},
        ...           prefix="doc")  # doctest: +SKIP
        <?xml version='1.0' encoding='utf-8'?>
        <doc:data xmlns:doc="https://example.com">
          <doc:row>
            <doc:index>0</doc:index>
            <doc:shape>square</doc:shape>
            <doc:degrees>360</doc:degrees>
            <doc:sides>4.0</doc:sides>
          </doc:row>
          <doc:row>
            <doc:index>1</doc:index>
            <doc:shape>circle</doc:shape>
            <doc:degrees>360</doc:degrees>
            <doc:sides/>
          </doc:row>
          <doc:row>
            <doc:index>2</doc:index>
            <doc:shape>triangle</doc:shape>
            <doc:degrees>180</doc:degrees>
            <doc:sides>3.0</doc:sides>
          </doc:row>
        </doc:data>
        r