How to use the mutmut.Context function in mutmut

def test_pragma_no_mutate():
    source = """def foo():\n    return 1+1  # pragma: no mutate\n"""
    assert mutate(Context(source=source, mutation_id=ALL)) == (source, 0)

def test_mutate_all():
    assert mutate(Context(source='def foo():\n    return 1+1', mutation_id=ALL)) == ('def foo():\n    return 2-2', 3)

def test_bug_github_issue_77():
    # Don't crash on this
    Context(source='')

def test_basic_mutations_python36(original, expected):
    actual = mutate(Context(source=original, mutation_id=ALL, dict_synonyms=['Struct', 'FooBarDict']))[0]
    assert actual == expected

def test_mutate_decorator():
    source = """@foo\ndef foo():\n    pass\n"""
    assert mutate(Context(source=source, mutation_id=ALL)) == (source.replace('@foo', ''), 1)

def _get_unified_diff(source, filename, mutation_id, dict_synonyms, update_cache):

    if update_cache:
        update_line_numbers(filename)

    if source is None:
        with open(filename) as f:
            source = f.read()
    context = Context(
        source=source,
        filename=filename,
        mutation_id=mutation_id,
        dict_synonyms=dict_synonyms,
    )
    mutated_source, number_of_mutations_performed = mutate(context)
    if not number_of_mutations_performed:
        return ""

    output = ""
    for line in unified_diff(source.split('\n'), mutated_source.split('\n'), fromfile=filename, tofile=filename, lineterm=''):
        output += line + "\n"
    return output

:param mutation_pk: mutmut cache primary key of the mutant to apply
    :type mutation_pk: str

    :param dict_synonyms: list of synonym keywords for a python dictionary
    :type dict_synonyms: list[str]

    :param backup: if :obj:`True` create a backup of the source file
        before applying the mutation
    :type backup: bool
    """
    filename, mutation_id = filename_and_mutation_id_from_pk(int(mutation_pk))

    update_line_numbers(filename)

    context = Context(
        mutation_id=mutation_id,
        filename=filename,
        dict_synonyms=dict_synonyms,
    )
    mutate_file(
        backup=backup,
        context=context,
    )