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