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Bob Gale and Christopher Lloyd , who had previously worked on the Back to the Future trilogy , worked on this film as well .
 person: Bob Gale; person: Christopher Lloyd
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Bob Gale, Christopher Lloyd 
Answer:
 person: Bob Gale; person: Christopher Lloyd