code: function positiveInteger(token, addTokenToMatch, getNextToken) {
      if (calc(token, addTokenToMatch, getNextToken)) {
          return true;
      }
  
      if (token === null) {
          return false;
      }
  
      var numberEnd = findDecimalNumberEnd(token.value, 0);
      if (numberEnd !== token.value.length || token.value.charCodeAt(0) === HYPHENMINUS) {
          return false;
      }
  
      addTokenToMatch();
      return true;
  }
docs: TODO: fail on 10e-2