How to use the pylatexenc.macrospec.LatexContextDb function in pylatexenc

def test_can_get_macro_spec(self):
        db = LatexContextDb()
        db.set_unknown_macro_spec(MacroSpec(''))
        db.add_context_category('cat1', [ std_macro('aaa', '{'), std_macro('bbb', '[{[') ], [])
        db.add_context_category('cat2', [ std_macro('aaa', '[{'), std_macro('ccc', None) ], [])
        db.add_context_category('cat3', [ std_macro('ccc', '*{'), std_macro('ddd', '{{[') ], [],
                                prepend=True)

        self.assertEqual(list(db.categories()), ['cat3', 'cat1', 'cat2'])
        
        self.assertEqual(db.get_macro_spec('aaa').macroname, 'aaa')
        self.assertEqual(db.get_macro_spec('aaa').args_parser.argspec, '{')

        self.assertEqual(db.get_macro_spec('bbb').macroname, 'bbb')
        self.assertEqual(db.get_macro_spec('bbb').args_parser.argspec, '[{[')

        self.assertEqual(db.get_macro_spec('ccc').macroname, 'ccc')
        self.assertEqual(db.get_macro_spec('ccc').args_parser.argspec, '*{')

def test_filter_context_0(self):
        
        db = LatexContextDb()
        db.set_unknown_macro_spec(MacroSpec(''))
        db.set_unknown_environment_spec(EnvironmentSpec(''))
        db.add_context_category('cat1',
                                [ std_macro('aaa', '{'), std_macro('bbb', '[{[') ],
                                [ std_environment('eaaa', '{'), std_environment('ebbb', '[{[') ])
        db.add_context_category('cat2',
                                [ std_macro('aaa', '[{'), std_macro('ccc', None) ],
                                [ std_environment('eaaa', '[{'), std_environment('eccc', None) ])
        db.add_context_category('cat3',
                                [ std_macro('ccc', '*{'), std_macro('ddd', '{{[') ],
                                [ std_environment('eccc', '*{'), std_environment('eddd', '{{[') ],
                                prepend=True)
        
        db2 = db.filter_context(keep_categories=['cat1', 'cat2'])
        # this should give 'ccc' from cat2, not cat3
        self.assertEqual(db2.get_macro_spec('ccc').macroname, 'ccc')

def test_filter_context_4(self):
        
        db = LatexContextDb()
        db.set_unknown_macro_spec(MacroSpec(''))
        db.set_unknown_environment_spec(EnvironmentSpec(''))
        db.add_context_category('cat1',
                                [ std_macro('aaa', '{'), std_macro('bbb', '[{[') ],
                                [ std_environment('eaaa', '{'), std_environment('ebbb', '[{[') ])
        db.add_context_category('cat2',
                                [ std_macro('aaa', '[{'), std_macro('ccc', None) ],
                                [ std_environment('eaaa', '[{'), std_environment('eccc', None) ])
        db.add_context_category('cat3',
                                [ std_macro('ccc', '*{'), std_macro('ddd', '{{[') ],
                                [ std_environment('eccc', '*{'), std_environment('eddd', '{{[') ],
                                prepend=True)
        
        db2 = db.filter_context(keep_categories=['cat1', 'cat3'], exclude_categories=['cat3'],
                                keep_which=['environments'])
        # no macros should exist any longer

def test_filter_context_2(self):
        
        db = LatexContextDb()
        db.set_unknown_macro_spec(MacroSpec(''))
        db.set_unknown_environment_spec(EnvironmentSpec(''))
        db.add_context_category('cat1',
                                [ std_macro('aaa', '{'), std_macro('bbb', '[{[') ],
                                [ std_environment('eaaa', '{'), std_environment('ebbb', '[{[') ])
        db.add_context_category('cat2',
                                [ std_macro('aaa', '[{'), std_macro('ccc', None) ],
                                [ std_environment('eaaa', '[{'), std_environment('eccc', None) ])
        db.add_context_category('cat3',
                                [ std_macro('ccc', '*{'), std_macro('ddd', '{{[') ],
                                [ std_environment('eccc', '*{'), std_environment('eddd', '{{[') ],
                                prepend=True)
        
        db2 = db.filter_context(keep_categories=['cat1', 'cat3'], exclude_categories=['cat3'])
        # this should give 'aaa' from cat1
        self.assertEqual(db2.get_macro_spec('aaa').macroname, 'aaa')

If you want to add your own definitions, you should use the
    :py:meth:`pylatexenc.macrospec.LatexContextDb.add_context_category()`
    method.  If you would like to override some definitions, use that method
    with the argument `prepend=True`.  See docs for
    :py:meth:`pylatexenc.macrospec.LatexContextDb.add_context_category()`.

    If there are too many macro/environment definitions, or if there are some
    irrelevant ones, you can always filter the returned database using
    :py:meth:`pylatexenc.macrospec.LatexContextDb.filter_context()`.

    .. versionadded:: 2.0
 
       The :py:class:`pylatexenc.macrospec.LatexContextDb` class as well as this
       method, were all introduced in `pylatexenc 2.0`.
    """
    db = macrospec.LatexContextDb()
    
    from ._defaultspecs import specs

    for cat, catspecs in specs:
        db.add_context_category(cat,
                                macros=catspecs['macros'],
                                environments=catspecs['environments'],
                                specials=catspecs['specials'])
    
    return db

If you want to add your own definitions, you should use the
    :py:meth:`pylatexenc.macrospec.LatexContextDb.add_context_category()`
    method.  If you would like to override some definitions, use that method
    with the argument `prepend=True`.  See docs for
    :py:meth:`pylatexenc.macrospec.LatexContextDb.add_context_category()`.

    If there are too many macro/environment definitions, or if there are some
    irrelevant ones, you can always filter the returned database using
    :py:meth:`pylatexenc.macrospec.LatexContextDb.filter_context()`.

    .. versionadded:: 2.0
 
       The :py:class:`pylatexenc.macrospec.LatexContextDb` class as well as this
       method, were all introduced in `pylatexenc 2.0`.
    """
    db = macrospec.LatexContextDb()
    
    from ._defaultspecs import specs

    for cat, catspecs in specs:
        db.add_context_category(cat,
                                macros=catspecs['macros'],
                                environments=catspecs['environments'],
                                specials=catspecs['specials'])
    
    return db

def __init__(self, latex_context=None, **flags):
        super(LatexNodes2Text, self).__init__()

        if latex_context is None:
            if 'macro_dict' in flags or 'env_dict' in flags:
                # LEGACY -- build a latex context using the given macro_dict
                _util.pylatexenc_deprecated_2(
                    "The `macro_dict=...` and `env_dict=...` options in LatexNodes2Text() are "
                    "obsolete since pylatexenc 2.  They will still work, but please consider "
                    "using instead the more versatile option `latex_context=...`."
                )
                
                macro_dict = flags.pop('macro_dict', [])
                env_dict = flags.pop('env_dict', [])

                latex_context = macrospec.LatexContextDb()
                latex_context.add_context_category('custom',
                                                   macros=macro_dict.values(),
                                                   environments=env_dict.values(),
                                                   specials=[])

            else:
                # default -- use default
                latex_context = get_default_latex_context_db()

        self.latex_context = latex_context

        self.tex_input_directory = None
        self.strict_input = True

        if 'keep_inline_math' in flags:
            if 'math_mode' in flags: