code: function(start, len) {
  
      var delta = 0;
  
      if ('number' === typeof start) {
  
        if ((start < 0) || (start >= get(this, 'length'))) {
          throw new Error(OUT_OF_RANGE_EXCEPTION);
        }
  
        // fast case
        if (len === undefined) len = 1;
        this.replace(start, len, EMPTY);
      }
  
      return this ;
    }
docs: Remove an object at the specified index using the replace() primitive
  method.  You can pass either a single index, or a start and a length.
  
  If you pass a start and length that is beyond the
  length this method will throw an Ember.OUT_OF_RANGE_EXCEPTION
  
  var colors = ["red", "green", "blue", "yellow", "orange"];
  colors.removeAt(0); => ["green", "blue", "yellow", "orange"]
  colors.removeAt(2, 2); => ["green", "blue"]
  colors.removeAt(4, 2); => Error: Index out of range
  
  @param {Number} start index, start of range
  @param {Number} len length of passing range
  @returns {Object} receiver