How to use the pycobertura.filesystem.filesystem_factory function in pycobertura

"""
        Initialize a Cobertura report given a coverage report `report`. It can
        be either a file object or the path to an XML file that is in the
        Cobertura format.

        The optional argument `filesystem` describes how to retrieve the source
        files referenced in the report. Please check the pycobertura.filesystem
        module in order to discover more about filesystems.
        """
        self.xml = ET.parse(report).getroot()
        self.report = report if isinstance(report, basestring) else None

        if filesystem:
            self.filesystem = filesystem
        else:
            self.filesystem = filesystem_factory(self.report)

def diff(
    cobertura_file1,
    cobertura_file2,
    color,
    format,
    output,
    source1,
    source2,
    source_prefix1,
    source_prefix2,
    source,
):
    """compare coverage of two Cobertura reports"""
    fs1 = filesystem_factory(
        report=cobertura_file1, source=source1, source_prefix=source_prefix1
    )
    fs2 = filesystem_factory(
        report=cobertura_file2, source=source2, source_prefix=source_prefix2
    )
    cobertura1 = Cobertura(cobertura_file1, filesystem=fs1)
    cobertura2 = Cobertura(cobertura_file2, filesystem=fs2)

    Reporter = delta_reporters[format]
    reporter_args = [cobertura1, cobertura2]
    reporter_kwargs = {"show_source": source}

    isatty = True if output is None else output.isatty()

    if format == "text":
        color = isatty if color is None else color is True

cobertura_file1,
    cobertura_file2,
    color,
    format,
    output,
    source1,
    source2,
    source_prefix1,
    source_prefix2,
    source,
):
    """compare coverage of two Cobertura reports"""
    fs1 = filesystem_factory(
        report=cobertura_file1, source=source1, source_prefix=source_prefix1
    )
    fs2 = filesystem_factory(
        report=cobertura_file2, source=source2, source_prefix=source_prefix2
    )
    cobertura1 = Cobertura(cobertura_file1, filesystem=fs1)
    cobertura2 = Cobertura(cobertura_file2, filesystem=fs2)

    Reporter = delta_reporters[format]
    reporter_args = [cobertura1, cobertura2]
    reporter_kwargs = {"show_source": source}

    isatty = True if output is None else output.isatty()

    if format == "text":
        color = isatty if color is None else color is True
        reporter_kwargs["color"] = color

    reporter = Reporter(*reporter_args, **reporter_kwargs)

def show(cobertura_file, format, output, source, source_prefix):
    """show coverage summary of a Cobertura report"""
    fs = filesystem_factory(cobertura_file, source=source)
    cobertura = Cobertura(cobertura_file, filesystem=fs)
    Reporter = reporters[format]
    reporter = Reporter(cobertura)
    report = reporter.generate()

    if not isinstance(report, bytes):
        report = report.encode("utf-8")

    isatty = True if output is None else output.isatty()
    click.echo(report, file=output, nl=isatty)