Python从类字符串中识别不同格式的日期

Question

我有文本输入。我要查一查这个字符串里有没有日期。挑战在于日期可以有很多不同的格式

datefinder.find_dates尝试使用txt输入。可以看到输入数据的类型

import datefinder

with open("Azurebill.txt") as open_file:

    data = open_file.read()
    data = data.upper()
    print('this type is:',  type(data))

def extractDate(input):

    matches = datefinder.find_dates(input)
    for match in matches:
        print ('The date match is ')
        return (match)

if __name__ == "__main__":
    b=extractDate(data)
    print(b)

Input[.txt]
------------
City Centre Durgapur (W. B. )
CIN:U15135DL 1991PLC046758
Ph. No. -08336967703
TIN NO. : 19200834072
STR NO. : AABCD5534AST002
INVOICE
Inv No 31416051984 ORD No 31416052092
Date: 11/09/16 7:26 POS No.
T31411
Staff : Ricky
Table
1
Cust.
Table 1
Token No: - 117
*DINE-IN*
THANK

实际结果：

this type is: <class 'str'>
The date match is
1991-06-11 00:00:00

预期结果

The date match is 11/09/16