code: function Concept(concept) {
    if (!(concept.prefLabel && concept.id && concept.type === 'Concept')) {
      throw new Error('Invalid concept: "' + concept.id + '"');
    }
    this.id = concept.id;
    this.prefLabel = concept.prefLabel;
    this.altLabel = concept.altLabel;
    this.hiddenLabel = concept.hiddenLabel;
    this.definition = concept.definition;
    this._topConceptOf = concept.topConceptOf;
    this._partOfScheme = false;
    this._originalConcept = concept;
    this._broaderConcepts = [];
    this._narrowerConcepts = [];
    this._relatedConcepts = [];
  }
docs: Concept class.
  
  A wrapper for the SKOS Concept JSON object
  
  @constructor
  @param {Object} concept - A Concept JSON object