text: import { ValueStateValue, RelationState } from '@uncharted.software/lex/dist/lex';
  const options = [
    ['from', 'from']
  ].map(o => new ValueStateValue(o[0], {}, { displayKey: o[1] }));
  // Adapted from binary relations
  export default class EdgeRelationState extends RelationState {
    /**
     * The "from" option.
     */
    static get SOURCE_IS () {
      return options[0];
    }
  
    constructor(config) {
      if (config.name === undefined) config.name = 'Choose a search option';
      config.options = function () {
        return options;
      };
      super(config);
    }
  }
  