code: function(dontDiscard, properties, value, equals)
    {
      function popIt(model)
      {
        model.$pop( dontDiscard );
      }
  
      return this.eachWhere( popIt, properties, value, equals );
    }
docs: Calls {@link Rekord.Model#$pop} on models in this collection that meet
  the given where expression.
  
  @method
  @memberof Rekord.ModelCollection#
  @param {Boolean} [dontDiscard=false] -
  Whether to remove the saved state after the saved state has been applied
  back to the model. A falsy value will result in
  {@link Rekord.Model#$discard} being called.
  @param {whereInput} [properties] -
  See {@link Rekord.createWhere}
  @param {Any} [value] -
  See {@link Rekord.createWhere}
  @param {equalityCallback} [equals=Rekord.equalsStrict] -
  See {@link Rekord.createWhere}
  @return {Rekord.ModelCollection} -
  The reference to this collection.
  @see Rekord.createWhere
  @see Rekord.Model#$pop