How to use the poetry.version.markers.parse_marker function in poetry

def test_marker_union_all_any():
    union = MarkerUnion(parse_marker(""), parse_marker(""))

    assert union.is_any()

def test_marker_union_union_duplicates():
    m = parse_marker('sys_platform == "darwin" or python_version < "3.4"')

    union = m.union(parse_marker('sys_platform == "darwin" or os_name == "Windows"'))
    assert str(union) == (
        'sys_platform == "darwin" or python_version < "3.4" or os_name == "Windows"'
    )

    m = parse_marker('sys_platform == "darwin" or python_version < "3.4"')

    union = m.union(
        parse_marker(
            'sys_platform == "darwin" or os_name == "Windows" or python_version <= "3.6"'
        )
    )
    assert str(union) == (
        'sys_platform == "darwin" or python_version <= "3.6" or os_name == "Windows"'
    )

def test_single_marker():
    m = parse_marker('sys_platform == "darwin"')

    assert isinstance(m, SingleMarker)
    assert m.name == "sys_platform"
    assert m.constraint_string == "==darwin"

    m = parse_marker('python_version in "2.7, 3.0, 3.1"')

    assert isinstance(m, SingleMarker)
    assert m.name == "python_version"
    assert m.constraint_string == "in 2.7, 3.0, 3.1"
    assert str(m.constraint) == ">=2.7.0,<2.8.0 || >=3.0.0,<3.2.0"

    m = parse_marker('"2.7" in python_version')

    assert isinstance(m, SingleMarker)
    assert m.name == "python_version"

def test_single_marker_union_compacts_constraints():
    m = parse_marker('python_version < "3.6"')

    union = m.union(parse_marker('python_version < "3.4"'))
    assert str(union) == 'python_version < "3.6"'

def test_single_marker_not_in_python_intersection():
    m = parse_marker('python_version not in "2.7, 3.0, 3.1"')

    intersection = m.intersect(
        parse_marker('python_version not in "2.7, 3.0, 3.1, 3.2"')
    )
    assert str(intersection) == 'python_version not in "2.7, 3.0, 3.1, 3.2"'

def test_multi_marker_union_multi():
    m = parse_marker('sys_platform == "darwin" and implementation_name == "cpython"')

    intersection = m.union(
        parse_marker('python_version >= "3.6" and os_name == "Windows"')
    )
    assert str(intersection) == (
        'sys_platform == "darwin" and implementation_name == "cpython" '
        'or python_version >= "3.6" and os_name == "Windows"'

def test_marker_union_not_all_empty():
    union = MarkerUnion(
        parse_marker(""), parse_marker(""), parse_marker("")
    )

    assert not union.is_empty()

def test_marker_union():
    m = parse_marker('sys_platform == "darwin" or implementation_name == "cpython"')

    assert isinstance(m, MarkerUnion)
    assert m.markers == [
        parse_marker('sys_platform == "darwin"'),
        parse_marker('implementation_name == "cpython"'),
    ]

if "marker" in info:
                package.marker = parse_marker(info["marker"])
            else:
                # Compatibility for old locks
                if "requirements" in info:
                    dep = poetry.packages.Dependency("foo", "0.0.0")
                    for name, value in info["requirements"].items():
                        if name == "python":
                            dep.python_versions = value
                        elif name == "platform":
                            dep.platform = value

                    split_dep = dep.to_pep_508(False).split(";")
                    if len(split_dep) > 1:
                        package.marker = parse_marker(split_dep[1].strip())

            for dep_name, constraint in info.get("dependencies", {}).items():
                if isinstance(constraint, list):
                    for c in constraint:
                        package.add_dependency(dep_name, c)

                    continue

                package.add_dependency(dep_name, constraint)

            if "source" in info:
                package.source_type = info["source"]["type"]
                package.source_url = info["source"]["url"]
                package.source_reference = info["source"]["reference"]

            packages.add_package(package)