def METHOD_NAME(chain):
    genesis = chain.get_canonical_block_by_number(0)
    block_1 = chain.mine_block()
    header = block_1.header
    assert header.block_number == 1
    assert chain.get_ancestors(0, header) == ()
    assert chain.get_ancestors(1, header) == (genesis,)
    assert chain.get_ancestors(2, header) == (genesis,)
    assert chain.get_ancestors(5, header) == (genesis,)