Definition: You are given a conversation between two people. 'Person1:' and 'Person2:' are used to separate their respective dialogues. You are required to assign a label 'formal' if there is an absence of emotion and a presence of questions anywhere within the conversation. If such pattern is not found assign the label 'informal'.
Input:  Person1:       What can I do for you today ?  
 Person2:I need to return a book .  
 Person1:        Can I do anything else for you ?  
 Person2:I want to check these books out .  
 Person1:        Is that all ?  
 Person2:That ’ s all .  
 Person1:        May I see your library card , please ?  
 Person2:It ’ s right here .  
 Person1:        Will that be all for today ?  
 Person2:Yes . That ’ s it .  
 Person1:        These are due back in two weeks .  
 Person2:All right . Have a good night . 

informal