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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _validate_pos(df):
 """Validates the returned positional object """

    assert isinstance(df, pd.DataFrame)
    assert ["seqname", "position", "strand"] == df.columns.tolist()
    assert df.position.dtype == np.dtype("int64")
    assert df.strand.dtype == np.dtype("O")
    assert df.seqname.dtype == np.dtype("O")
    return df