code: def get_cell(self, index, column):
          
          i = sorted_index(self._index, index) if self._sort else self._index.index(index)
          c = self._columns.index(column)
          return self._data[c][i]
docs: For a single index and column value return the value of the cell
  
          :param index: index value
          :param column: column name
          :return: value