Python 删除textfile中的重复行-除非它包含一个"；{"；或"；}"；

我有一个非常大的文本文件，内容如下：

@INBOOK{Ackermann1999-b, 
  author = {Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, 
        K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. 
        and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and 
        Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, 
        K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. 
        and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and 
        Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, 
        K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. 
        and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and 
        Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann}, 
  year = {1980}, 
  timestamp = {1995-12-02} 
}      

我想删除重复的行，除了这些包含括号{或}的行。 结果应该如下所示：

@INBOOK{Ackermann1999-b, 
  author = {Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, 
        Ackermann, K.-F. and Ackermann, K.-F. and Ackermann, K.-F. and Ackermann}, 
  year = {1980}, 
  timestamp = {1995-12-02} 
} 

多亏了Vinay Sajip，我遇到了这个Python脚本：

lines_seen = set() # holds lines already seen 
outfile = open("literatur_clean.txt", "w") 
for line in open("literatur_dupl.txt", "r"): 
    if line not in lines_seen: # not a duplicate 
        outfile.write(line) 
        lines_seen.add(line) 
outfile.close() 

但它也会删除带有右括号}的行和具有相同authordata的行。 因此，我需要括号的条件

有人能指出我加入这个条件吗

---

提前感谢，

感谢eumiro，只需稍加修改“或”代替“和”即可完美工作：如果（“{”在行中或“}”在行中）或行中未看到：

if ('{' in line or '}' in line) and line not in lines_seen: # not a duplicate