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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_case_lists(study_id):
 """Return a list of the case set ids for a particular study. TAKE NOTE the "case_list_id" are the same thing as "case_set_id" Within the data, this string is referred to as a "case_list_id". Within API calls it is referred to as a 'case_set_id'. The documentation does not make this explicitly clear. Parameters study_id : str The ID of the cBio study. Example: 'cellline_ccle_broad' or 'paad_icgc' Returns ------- case_set_ids : dict[dict[int]] A dict keyed to cases containing a dict keyed to genes containing int """

    data = {'cmd': 'getCaseLists',
            'cancer_study_id': study_id}
    df = send_request(**data)
    case_set_ids = df['case_list_id'].tolist()
    return case_set_ids