How to sum the values of a JavaScript object

Question

I'd like to sum the values of an object.

I'm used to python where it would just be:

sample = { 'a': 1 , 'b': 2 , 'c':3 };
summed =  sum(sample.itervalues()) 

The following code works, but it's a lot of code:

function obj_values(object) {
  var results = [];
  for (var property in object)
    results.push(object[property]);
  return results;
}

function list_sum( list ){
  return list.reduce(function(previousValue, currentValue, index, array){
      return previousValue + currentValue;
  });
}

function object_values_sum( obj ){
  return list_sum(obj_values(obj));
}

var sample = { a: 1 , b: 2 , c:3 };
var summed =  list_sum(obj_values(a));
var summed =  object_values_sum(a)

Am i missing anything obvious, or is this just the way it is?