function application(s) {
    var x = symbol(s, 42);

    x.infix = true;
    x.led = function(context, left) {
      nobreaknonadjacent(state.tokens.prev, state.tokens.curr);

      this.left = left;
      this.right = doFunction(context, { type: "arrow", loneArg: left });
      return this;
    };
    return x;
  }
Convenience function for defining the `=>` token as used in arrow
functions.

@param {string} s - the name of the symbol

@returns {object} - the object describing the JSHint symbol (provided to
                    support cases where further refinement is necessary)