def __init__(self, milestone_id=None):
        self.milestone_id = milestone_id
        self.labels = []
        self.sections = {}
        self.contributors = set()
        self.__add_section("feature", ChangelogSection("New Features"))
        self.__add_section("performance", ChangelogSection("Performance Improvements"))
        self.__add_section("fix", ChangelogSection("Fixes"))
        self.__add_section("internal", ChangelogSection("Internal Improvements"))