code: public ImmutableFormulaList encode(final PBConstraint cc) {
      final EncodingResult result = EncodingResult.resultForFormula(f);
      this.encodeConstraint(cc, result);
      return new ImmutableFormulaList(FType.AND, result.result());
    }
docs: Encodes a cardinality constraint and returns its CNF encoding.
  @param cc the cardinality constraint
  @return the CNF encoding of the cardinality constraint