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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 get_valid_statements_for_modeling(sts: List[Influence]) -> List[Influence]: """ Select INDRA statements that can be used to construct a Delphi model from a given list of statements. """


    return [
        s
        for s in sts
        if is_grounded_statement(s)
        and (s.subj_delta["polarity"] is not None)
        and (s.obj_delta["polarity"] is not None)
    ]