'Create a delete document and add it to the list of ops.'

def add_delete(self, selector, limit, collation=None):

    cmd = SON([('q', selector), ('limit', limit)])
    collation = validate_collation_or_none(collation)
    if (collation is not None):
        self.uses_collation = True
        cmd['collation'] = collation
    self.ops.append((_DELETE, cmd))
