code: def write_var_column(self, column, data, firstrow=0, **keys):
          
  
          if not is_object(data):
              raise ValueError("Only object fields can be written to "
                               "variable-length arrays")
          colnum = self._extract_colnum(column)
  
          self._FITS.write_var_column(self._ext+1, colnum+1, data,
                                      firstrow=firstrow+1)
          self._update_info()
docs: Write data to a variable-length column in this HDU
  
          This HDU must be a table HDU.
  
          parameters
          ----------
          column: scalar string/integer
              The column in which to write.  Can be the name or number (0 offset)
          column: ndarray
              Numerical python array to write.  This must be an object array.
          firstrow: integer, optional
              At which row you should begin writing.  Be sure you know what you
              are doing!  For appending see the append() method.  Default 0.