Something

def get_needed_packages(package):    unresolved = Set()    unresolved.add(package)    resolved = Set()    while len(unresolved) > 0:        pkg = unresolved.pop()        resolved.add(pkg)        for dep in pkg.deps():            p = manager.get_package(dep[-1])            if p not in resolved:                unresolved.add(p)    return resolved