def get_installed_pypackages():
    return {p.project_name.lower(): p for p in pkg_resources.working_set}
def kth(root, k):
    if k < size(root.left):
        return kth(root.left, k)
    elif k > size(root.left):
        return kth(root.right, k - size(root.left) - 1)
    return root.key