code: public static Relation relation() {
  		Relation ret = X.relation();
  		ASTNode an = APIObjectAccess.getAstNode(ret);
  		an.setClauseType(ClauseType.CREATE_UNIQUE);
  		return ret;
  	}
docs: <div color='red' style="font-size:24px;color:red"><b><i><u>JCYPHER</u></i></b></div>
  <div color='red' style="font-size:18px;color:red"><i>create a relation</i></div>
  <div color='red' style="font-size:18px;color:red"><i>e.g. <b>CREATE_UNIQUE.relation()</b></i></div>
  <br/>