Return a :class:`Collection` with the specified properties.

	Args:
		iterable (Iterable): collection to instantiate new collection from.
		mutable (bool): Whether or not the new collection is mutable.
		ordered (bool): Whether or not the new collection is ordered.
		unique (bool): Whether or not the new collection contains only unique values.

def collection(iterable=None, mutable=True, ordered=False, unique=False):
	"""Return a :class:`Collection` with the specified properties.

	Args:
		iterable (Iterable): collection to instantiate new collection from.
		mutable (bool): Whether or not the new collection is mutable.
		ordered (bool): Whether or not the new collection is ordered.
		unique (bool): Whether or not the new collection contains only unique values.
	"""
	if iterable is None:
		iterable = tuple()
	if unique:
		if ordered:
			if mutable:
				return setlist(iterable)
			else:
				return frozensetlist(iterable)
		else:
			if mutable:
				return set(iterable)
			else:
				return frozenset(iterable)
	else:
		if ordered:
			if mutable:
				return list(iterable)
			else:
				return tuple(iterable)
		else:
			if mutable:
				return bag(iterable)
			else:
				return frozenbag(iterable)