ST_Simplify(provided by PostGIS) and GeoDjango

ST_Simplify function is provided by PostGIS.
It is used to simplify the geometry(eg. LINESTRING or POLYGON).
It use `simplify` method of GEOSGeometry class.
Django version is 1.3.

>>> line_string.simplify?
Type:           instancemethod
Base Class:     <type 'instancemethod'>
String Form:    <bound method LineString.simplify of <LineString object at 0xa4ed5f0>>
Namespace:      Interactive
File:           /usr/local/lib/python2.6/dist-packages/Django-1.3-py2.6.egg/django/contrib/gis/geos/geometry.py
Definition:     line_string.simplify(self, tolerance=0.0, preserve_topology=False)
...
>>> line_string
<LineString object at 0xa4ed5f0>
>>> len(line_string)
4367
>>> line_string[:3]
[(138.67654300000001, 35.492500999999997, 944.62300000000005), (138.676545, 35.4925, 944.62300000000005), (138.676546, 35.492499000000002, 944.63)]
>>> simplified = line_string.simplify(0.001)
>>> len(simplified)
90
>>> simplified2 = line_string.simplify(0.001, True)
>>> len(simplified2)
2458