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:       How may I help you ?  
 Person2:I would like to return this book .  
 Person1:        Is that all you need ?  
 Person2:I also want to check out this video .  
 Person1:        Is that all you would like to check out ?  
 Person2:That ’ s all I need .  
 Person1:        Do you have your library card ?  
 Person2:Here it is .  
 Person1:        Make sure to take proper care of this video .  
 Person2:That won ’ t be a problem .  
 Person1:        If you damage the video , you will be fined .  
 Person2:I won ’ t damage it . 

formal