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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 qc_curve_group(self, tests, alias=None):
 """ Run tests on a cohort of curves. Args: alias (dict):
 an alias dictionary, mapping mnemonics to lists of mnemonics. Returns: dict. """

        keys = [k for k, v in self.data.items() if isinstance(v, Curve)]
        if not keys:
            return {}

        all_tests = tests.get('all', tests.get('All', tests.get('ALL', [])))
        data = {test.__name__: test(self, keys, alias) for test in all_tests}

        results = {}
        for i, key in enumerate(keys):
            this = {}
            for test, result in data.items():
                this[test] = result[i]
            results[key] = this
        return results