code: function(paramSize, name, isSimple) {
                  this.aliases.helperMissing = 'helpers.helperMissing';
  
                  var nonHelper = this.popStack();
                  var helper = this.setupHelper(paramSize, name);
  
                  var lookup = (isSimple ? helper.name + ' || ' : '') + nonHelper + ' || helperMissing';
                  this.push('((' + lookup + ').call(' + helper.callParams + '))');
              }
docs: [invokeHelper]  On stack, before: hash, inverse, program, params..., ... On stack, after: result of helper invocation  Pops off the helper's parameters, invokes the helper, and pushes the helper's return value onto the stack.  If the helper is not found, `helperMissing` is called.