def add_package_dependency(self, package_name, version):
        """
        Add a package to the list of dependencies.

        :param package_name: The name of the package dependency
        :type package_name: str
        :param version: The (minimum) version of the package
        :type version: str
        """
        if not PEP440_VERSION_PATTERN.match(version):
            raise ValueError('Invalid Version: "{}"'.format(version))
        self.dependencies.add(PackageDependency(package_name, version))

        Add a package to the list of dependencies.

        :param package_name: The name of the package dependency
        :type package_name: str
        :param version: The (minimum) version of the package
        :type version: str
        
sacred/ingredient.py