def METHOD_NAME():
    s = vaex.string_column(["aap", None, "noot", "mies"])
    o = ["aap", None, "noot", np.nan]
    x = np.arange(4, dtype=np.float64)
    x[2] = x[3] = np.nan
    m = np.ma.array(x, mask=[0, 1, 0, 1])
    df = vaex.from_arrays(x=x, m=m, s=s, o=o)
    x = df.x.dropmissing().tolist()
    assert (9 not in x)
    assert np.any(np.isnan(x)), "nan is not a missing value"
    m = df.m.dropmissing().tolist()
    assert (m[:1] == [0])
    assert np.isnan(m[1])
    assert len(m) == 2
    assert (df.s.dropmissing().tolist() == ["aap", "noot", "mies"])
    assert (df.o.dropmissing().tolist()[:2] == ["aap", "noot"])
    # this changed in vaex 4, since the np.nan is considered missing, the whole
    # columns is seen as string
    # assert np.isnan(df.o.dropmissing().tolist()[2])