'Deletes one instance'

def delete(self):

    if (self.instance is None):
        raise CQLEngineException('DML    Query    instance    attribute    is    None')
    ds = DeleteStatement(self.column_family_name, timestamp=self._timestamp, conditionals=self._conditional, if_exists=self._if_exists)
    for (name, col) in self.model._primary_keys.items():
        val = getattr(self.instance, name)
        if ((val is None) and (not col.partition_key)):
            continue
        ds.add_where(col, EqualsOperator(), val)
    self._execute(ds)
