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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 isQCValid(self):
 """ Returns True if the results of the last batch of QC Analyses performed against this instrument was within the valid range. For a given Reference Sample, more than one Reference Analyses assigned to this same instrument can be performed and the Results Capture Date might slightly differ amongst them. Thus, this function gets the latest QC Analysis performed, looks for siblings (through RefAnalysisGroupID) and if the results for all them are valid, then returns True. If there is one single Reference Analysis from the group with an out-of-range result, the function returns False """

        query = {"portal_type": "ReferenceAnalysis",
                 "getInstrumentUID": self.UID(),
                 "sort_on": "getResultCaptureDate",
                 "sort_order": "reverse",
                 "sort_limit": 1,}
        brains = api.search(query, CATALOG_ANALYSIS_LISTING)
        if len(brains) == 0:
            # There are no Reference Analyses assigned to this instrument yet
            return True

        # Look for siblings. These are the QC Analyses that were created
        # together with this last ReferenceAnalysis and for the same Reference
        # Sample. If they were added through "Add Reference Analyses" in a
        # Worksheet, they typically appear in the same slot.
        group_id = brains[0].getReferenceAnalysesGroupID
        query = {"portal_type": "ReferenceAnalysis",
                 "getInstrumentUID": self.UID(),
                 "getReferenceAnalysesGroupID": group_id,}
        brains = api.search(query, CATALOG_ANALYSIS_LISTING)
        for brain in brains:
            results_range = brain.getResultsRange
            if not results_range:
                continue
            # Is out of range?
            out_of_range = is_out_of_range(brain)[0]
            if out_of_range:
                return False

        # By default, in range
        return True