code: def search_unique(self, table_name, sample, unique_fields=None):
          
          return search_unique(table=self.table(table_name),
                               sample=sample,
                               unique_fields=unique_fields)
docs: Search in `table` an item with the value of the `unique_fields` in the `data` sample.
          Check if the the obtained result is unique. If nothing is found will return an empty list,
          if there is more than one item found, will raise an IndexError.
  
          Parameters
          ----------
          table_name: str
  
          sample: dict
              Sample data
  
          unique_fields: list of str
              Name of fields (keys) from `data` which are going to be used to build
              a sample to look for exactly the same values in the database.
              If None, will use every key in `data`.
  
          Returns
          -------
          eid: int
              Id of the object found with same `unique_fields`.
              None if none is found.
  
          Raises
          ------
          MoreThanOneItemError
              If more than one example is found.