How to use the cairosvg.surface.PNGSurface function in CairoSVG

def test_low_level_api():
    """Test the low-level Python API with various parameters."""
    _png_filename, svg_filename = FILES[0]
    expected_content = cairosvg.svg2png(url=svg_filename)

    # Same as above, longer version
    tree = cairosvg.parser.Tree(url=svg_filename)
    file_like = io.BytesIO()
    surface = cairosvg.surface.PNGSurface(tree, file_like, 96)
    surface.finish()
    assert file_like.getvalue() == expected_content

    png_result = png.Reader(bytes=expected_content).read()
    expected_width, expected_height, _, _ = png_result

    # Abstract surface
    surface = cairosvg.surface.PNGSurface(tree, None, 96)
    assert surface.width == expected_width
    assert surface.height == expected_height
    assert cairo.SurfacePattern(surface.cairo).get_surface() is surface.cairo
    assert_raises(TypeError, cairo.SurfacePattern, 'Not a cairo.Surface.')

"""Test the low-level Python API with various parameters."""
    _png_filename, svg_filename = FILES[0]
    expected_content = cairosvg.svg2png(url=svg_filename)

    # Same as above, longer version
    tree = cairosvg.parser.Tree(url=svg_filename)
    file_like = io.BytesIO()
    surface = cairosvg.surface.PNGSurface(tree, file_like, 96)
    surface.finish()
    assert file_like.getvalue() == expected_content

    png_result = png.Reader(bytes=expected_content).read()
    expected_width, expected_height, _, _ = png_result

    # Abstract surface
    surface = cairosvg.surface.PNGSurface(tree, None, 96)
    assert surface.width == expected_width
    assert surface.height == expected_height
    assert cairo.SurfacePattern(surface.cairo).get_surface() is surface.cairo
    assert_raises(TypeError, cairo.SurfacePattern, 'Not a cairo.Surface.')

def test_low_level_api():
    """Test the low-level Python API with various parameters."""
    expected_content = svg2png(SVG_SAMPLE)

    # Same as above, longer version
    tree = parser.Tree(bytestring=SVG_SAMPLE)
    file_like = io.BytesIO()
    png_surface = surface.PNGSurface(tree, file_like, 96)
    png_surface.finish()
    assert file_like.getvalue() == expected_content

    png_result = cairo.ImageSurface.create_from_png(
        io.BytesIO(expected_content))
    expected_width = png_result.get_width()
    expected_height = png_result.get_height()

    # Abstract surface
    png_surface = surface.PNGSurface(tree, None, 96)
    assert png_surface.width == expected_width
    assert png_surface.height == expected_height
    assert cairo.SurfacePattern(png_surface.cairo)

expected_content = svg2png(SVG_SAMPLE)

    # Same as above, longer version
    tree = parser.Tree(bytestring=SVG_SAMPLE)
    file_like = io.BytesIO()
    png_surface = surface.PNGSurface(tree, file_like, 96)
    png_surface.finish()
    assert file_like.getvalue() == expected_content

    png_result = cairo.ImageSurface.create_from_png(
        io.BytesIO(expected_content))
    expected_width = png_result.get_width()
    expected_height = png_result.get_height()

    # Abstract surface
    png_surface = surface.PNGSurface(tree, None, 96)
    assert png_surface.width == expected_width
    assert png_surface.height == expected_height
    assert cairo.SurfacePattern(png_surface.cairo)

# Frozen with something else (py2exe, etc.)
        # See https://github.com/Kozea/WeasyPrint/pull/269
        ROOT = Path(os.path.dirname(sys.executable))
else:
    ROOT = Path(os.path.dirname(__file__))

VERSION = __version__ = (ROOT / 'VERSION').read_text().strip()


# VERSION is used in the "url" module imported by "surface"
from . import surface  # noqa isort:skip


SURFACES = {
    'PDF': surface.PDFSurface,
    'PNG': surface.PNGSurface,
    'PS': surface.PSSurface,
    'SVG': surface.SVGSurface,
}


def svg2svg(bytestring=None, *, file_obj=None, url=None, dpi=96,
            parent_width=None, parent_height=None, scale=1, unsafe=False,
            background_color=None, negate_colors=False, invert_images=False,
            write_to=None, output_width=None, output_height=None):
    return surface.SVGSurface.convert(
        bytestring=bytestring, file_obj=file_obj, url=url, dpi=dpi,
        parent_width=parent_width, parent_height=parent_height, scale=scale,
        background_color=background_color,
        negate_colors=negate_colors, invert_images=invert_images,
        unsafe=unsafe, write_to=write_to, output_width=output_width,
        output_height=output_height)