code: function concatenation() {
      var ret = this.seq(
          repetition,
          this.manyf(this.seqf(
              this.many1f(c_wsp),
              repetition)));
      if (ret[2].length === 0) {
          return ret[1];
      }
      var cats = ret[2].map(function(el){ return el[2]; });
      return [].concat(ret[1]).concat(cats);
  }
docs: concatenation  =  repetition *(1*c-wsp repetition)