Python mechanize使用变量或提取的文本填充表单

我正在尝试使用python mechanize制作一个脚本来自动填充表单。具有根据其他因素变化的值。有没有办法让它从文件中读取？这是我的代码：

br.open('https://url/url)
br.select_form(nr=0)
br.form['xxxxx']='123456'
br.form['yyyyy']='7890'
br.submit()                                           
print br.response().read()

我怎么能得到这样的东西

br.form['xxxx']=open（xxx.txt，r）

因此，它读取xxx.txt并填写表单。。在网上似乎找不到任何东西

br.form['xxxx']=open(xxx.txt,r).read()

这将直接给出文件的内容

---

这将直接给出文件的内容。

如果txt文件只有一行，请尝试此操作

br.open(url)
br.select_form(nr=0)
with open('example.txt', 'r') as f:
    for line in f:
        br.form['xxxxx']= line
br.form['yyyyy']='7890'
response = br.submit()
search = response.read()

另一方面：

br.open(url)
br.select_form(nr=0)
lines = [line.rstrip('\n') for line in open('example.txt')]
br.form['xxxxx']= lines[0]
br.form['yyyyy']= lines[1]
response = br.submit()
search = response.read()

---

如果txt文件只有一行，请尝试此操作

br.open(url)
br.select_form(nr=0)
with open('example.txt', 'r') as f:
    for line in f:
        br.form['xxxxx']= line
br.form['yyyyy']='7890'
response = br.submit()
search = response.read()

另一方面：

br.open(url)
br.select_form(nr=0)
lines = [line.rstrip('\n') for line in open('example.txt')]
br.form['xxxxx']= lines[0]
br.form['yyyyy']= lines[1]
response = br.submit()
search = response.read()