code: def discrete(self, *args):
          
          new_df = copy_df(self)
          fields = _render_field_set(args)
          self._assert_ml_fields_valid(*fields)
          new_df._perform_operation(op.FieldContinuityOperation(dict((_get_field_name(f), False) for f in fields)))
          return new_df
docs: Set fields to be discrete.
  
          :rtype: DataFrame
  
          :Example:
  
          >>> # Table schema is create table test(f1 double, f2 string)
          >>> # Original continuity: f1=CONTINUOUS, f2=CONTINUOUS
          >>> # Now we want to set ``f1`` and ``f2`` into continuous
          >>> new_ds = df.discrete('f1 f2')