code: public JSONArray toJSON(Collection<SatConstraint> e) throws JSONConverterException {
          JSONArray arr = new JSONArray();
          for (SatConstraint cstr : e) {
              arr.add(toJSON(cstr));
          }
          return arr;
      }
docs: Serialise a list of sat-constraints.
  @param e the list to serialise
  @return the resulting encoded list
  @throws JSONConverterException if the conversion failed