def save(self):
ret = False<EOL>pk = None<EOL>if self.schema.pk.name not in self.modified_fields:<EOL><INDENT>pk = self.pk<EOL><DEDENT>if pk:<EOL><INDENT>ret = self.update()<EOL><DEDENT>else:<EOL><INDENT>ret = self.insert()<EOL><DEDENT>return ret<EOL>
persist the fields in this object into the db, this will update if _id is set, otherwise
it will insert

see also -- .insert(), .update()