code: def do_get_dataset(data, key, create=False):
          
          if data is None:
              return None
          try:
              return data[key]
          except KeyError:
              if create:
                  dataset = {}
                  data[key] = dataset
                  return dataset
              else:
                  raise
docs: Get a dataset.
  
          Parameters
          ----------
          data : `None` or `dict` of `dict` of ([`int`, `str`] or [`list` of `int`, `list` of `str`])
              Data.
          key : `str`
              Dataset key.
          create : `bool`, optional
              Create a dataset if it does not exist.
  
          Returns
          -------
          `None` or `dict` of ([`int`, `str`] or [`list` of `int`, `list` of `str`])