def load(self, filename, create_if_missing=True):
        filename = Path(filename)
        if not filename.exists() and create_if_missing:
            self.load_pip_requirements()
            with filename.open("w") as f:
                f.write(yaml.dump(self.serialized, default_flow_style=False,
                                  encoding=None))
            self.filename = filename
            return self.save(filename)
        with filename.open() as f:
            for group, requirements in yaml.load(f.read()).items():
                for requirement in requirements:
                    self[group].add(Requirement.coerce(requirement))
        self.filename = filename
def from_mapping(
        self, mapping: t.Optional[t.Mapping[str, t.Any]] = None, **kwargs: t.Any
    ) -> bool:
        """Updates the config like :meth:`update` ignoring items with non-upper
        keys.

        .. versionadded:: 0.11
        """
        mappings: t.Dict[str, t.Any] = {}
        if mapping is not None:
            mappings.update(mapping)
        mappings.update(kwargs)
        for key, value in mappings.items():
            if key.isupper():
                self[key] = value
        return True