def _extract_requirements(
        self,
        fields,
        requirements
    ):
        for name, field in six.iteritems(fields):
            source = field.source
            # Requires may be manually set on the field -- if not,
            # assume the field requires only its source.
            requires = getattr(field, 'requires', None) or [source]
            for require in requires:
                if not require:
                    # ignore fields with empty source
                    continue

                requirement = require.split('.')
                if requirement[-1] == '':
                    # Change 'a.b.' -> 'a.b.*',
                    # supporting 'a.b.' for backwards compatibility.
                    requirement[-1] = '*'
                requirements.insert(requirement, TreeMap(), update=True)
The infimum of 'self'
dataset/ETHPy150Open AltSchool/dynamic-rest/dynamic_rest/filters.py/DynamicFilterBackend._extract_requirements--crossover with--dataset/ETHPy150Open sympy/sympy/sympy/sets/sets.py/Set.inf