MongoDB: Function Not Defined During Mapreduce

I am running mapreduce on a collection with 1.15M documents. In the case of duplicates, when I return a result, I want to prefer some documents values over others (i.e. a field value in one document may be more accurate than another's, but then again might not exist at all).

To choose a value, I define this function (arguments are in the order of most preferred to least preferred):

function getPreferredValue() {
var length = arguments.length;
for (var i = 0; i < length; i++) {
    if (arguments[i] != null) {
        return arguments[i];
    }
}
return null;
}

My mapreduce command looks like this:

db.runCommand({
mapreduce:"catalog",
query: {$or:[
    {name:/^HIP/i},
    {name:/^SAO/i}
]},
map:function() {
    emit({dummy:this.xref}, this); // give me the whole damn object then
},
reduce:function(key, values) {
    var tempObject = {hipObject: null, saoObject:null};
    for (var i = 0; i < values.length; i++) {
        if (values[i].name.search("/^HIP") != -1) {
            var hipObject = {bii: null, lii: null, class: null, radeg: null, decdeg: null, rapm:null, decpm:null, vmag:null, parallax:null, xref:null};
            hipObject.bii = values[i].bii;
            hipObject.lii = values[i].lii;
            hipObject.class = values[i].class;
            hipObject.radeg = values[i].radeg;
            hipObject.decdec = values[i].decdeg;
            hipObject.rapm = values[i].rapm;
            hipObject.decpm = values[i].decpm;
            hipObject.vmag = values[i].vmag;
            hipObject.parallax = values[i].parallax;
            hipObject.xref = values[i].xref;
            tempObject.hipObject = hipObject;
        }
        if (values[i].name.search("/^SAO") != -1) {
            var saoObject = {bii: null, lii: null, class: null, radeg: null, decdeg: null, rapm:null, decpm:null, vmag:null, parallax:null, xref:null};
            saoObject.bii = values[i].bii;
            saoObject.lii = values[i].lii;
            saoObject.class = values[i].class;
            saoObject.radeg = values[i].radeg;
            saoObject.decdec = values[i].decdeg;
            saoObject.rapm = values[i].rapm;
            saoObject.decpm = values[i].decpm;
            saoObject.vmag = values[i].vmag;
            saoObject.parallax = values[i].parallax;
            saoObject.xref = values[i].xref;
            tempObject.saoObject = saoObject;
        }
    }

    var result = {bii: null, lii: null, class: null, radeg: null, decdeg: null, rapm:null, decpm:null, vmag:null, parallax:null, xref:null}
    result.bii = getPreferredValue(tempObject.hipObject.bii, tempObject.saoObject.bii);
    result.lii = getPreferredValue(tempObject.hipObject.lii, tempObject.saoObject.lii);
    result.class = getPreferredValue(tempObject.hipObject.class, tempObject.saoObject.class);
    result.radeg = getPreferredValue(tempObject.hipObject.radeg, tempObject.saoObject.radeg);
    result.decdeg = getPreferredValue(tempObject.hipObject.decdeg, tempObject.saoObject.decdeg);
    result.rapm = getPreferredValue(tempObject.hipObject.rapm, tempObject.saoObject.rapm);
    result.decpm = getPreferredValue(tempObject.hipObject.decpm, tempObject.saoObject.decpm);
    result.vmag = getPreferredValue(tempObject.hipObject.vmag, tempObject.saoObject.vmag);
    result.parallax = getPreferredValue(tempObject.hipObject.parallax, tempObject.saoObject.parallax);
    result.xref = tempObject.hipObject.xref;

    return result;
},
out: {replace:"catalog2", db:"astro3"}
});

Unfortunately, when attempting to run, I get an error that getPreferredValue is not defined.

Probably a stupid error on my part, but can anyone assist? Jason