customer: Hello. 
 agent: Hello. How may I help you today? 
 customer: I want to depart in the evening to meet my cousin, can you help me with booking? 
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 customer: My airport codes are OAK to IAD. 
 agent: Sure, may I know your travelling dates? 
 customer: My travelling dates are Apr 09 and Apr 11. 
 agent: On which name shall I reserve flight ticket? 
 customer: I am William Lee. 
 agent:  Sorry, there are no flights found on given dates. 
 customer: Ok, no problem. 
 agent: Thank you for reaching us. 
 customer: Thank you for your information.
agent: Sure, may I know your airport codes?