def test_drop_obs_column():
    adata = ad.AnnData(np.array(X_list), obs=obs_dict, dtype="int32")

    subset = adata[:2]
    assert subset.is_view
    # returns a copy of obs
    assert subset.obs.drop(columns=["oanno1"]).columns.tolist() == ["oanno2", "oanno3"]
    assert subset.is_view
    # would modify obs, so it should actualize subset and not modify adata
    subset.obs.drop(columns=["oanno1"], inplace=True)
    assert not subset.is_view
    assert subset.obs.columns.tolist() == ["oanno2", "oanno3"]

    assert adata.obs.columns.tolist() == ["oanno1", "oanno2", "oanno3"]
def _explicitfiles(kindpats):
    """Returns the potential explicit filenames from the patterns.

    >>> _explicitfiles([(b'path', b'foo/bar', b'')])
    ['foo/bar']
    >>> _explicitfiles([(b'rootfilesin', b'foo/bar', b'')])
    []
    """
    # Keep only the pattern kinds where one can specify filenames (vs only
    # directory names).
    filable = [kp for kp in kindpats if kp[0] not in ("rootfilesin",)]
    return _roots(filable)