if it exists.
_.filter = (obj, iterator, context) ->
  return obj.filter iterator, context if nativeFilter and obj.filter is nativeFilter
  results = []
  _.each obj, (value, index, list) ->
    results.push value if iterator.call context, value, index, list
  results


# Return all the elements for which a truth test fails.
_.reject = (obj, iterator, context) ->
  results = []
  _.each obj, (value, index, list) ->
    results.push value if not iterator.call context, value, index, list
  results


# Determi