```
allname = []
alltel = []
allemail = []

for link in docdetail:
            name = soup.h1.contents[1]
            tel = soup.find('a', class_='tel').string
            email = soup.find('a', class_='email').string
            allname.append(name)
            alltel.append(tel)
            allemail.append(email)

```

I want to append name to allname, tel to alltel, email to allemail after every for loop. But it is possible that the returned value for name/tel/email is empty, then he order of attributes may mess up. 
I want to assign "NA" to the variable if the returned values are empty. How should I write a code for this precisely?