Type Checking with leFunc

api-one.js

// Call api.one with any argument combo

api.one = leFunc({
          "String, Function":
  function(id    , callback){
    api.one(new ObjectId(id), {}, callback);
  }

,         "Object, Function":
  function(id    , callback){
    api.one(id, {}, callback);
  }

,         "String, Object, Function":
  function(id    , fields, callback){
    api.one(new ObjectId(id), fields, callback);
  }

,         "Object, Object, Function":
  function(id    , fields, callback){
    var data = (id instanceof ObjectId) ? { _id: id } : id;
    this.collection.findOne({ _id: id }, fields, callback);
  }
});