def METHOD_NAME():
    assert db.get_halo("sim/ts1/1").calculate('link(testlink)')["testval"] == 1.0
    assert db.get_halo("sim/ts1/1").calculate('link(testlink,testval)')["testval"] == 3.0
    assert db.get_halo("sim/ts1/1").calculate('link(testlink,testval,"min")')["testval"] == 0.0
    assert db.get_halo("sim/ts1/1").calculate('link(testlink,testval,"max",testval2>10,testval2<40)')["testval"] == 3.0