Goal: use the known_addresses to build a data structure and/or function that allows us to assign a zipcode to addresses on Broadway that are missing them when we have enough information. 
Return the zipcode if we can figure out what it is based on the info we have, otherwise return None
 Assumptions: 1. if 2 addresses are on the same•street-in the city, state, and zipcode, all addresses between them on that street are in the same zipcode (in other words, zipcodes are continuous along streets) 2. nothing we care about is case sensitive 3. we are allowed to modify known_addresses ahead of time however we want (ex: rearrange the list, different data structure, delete elements) 4. All street numbers are valid positive integers 5. We only need to return results for Broadway, New York-NY; addresses on other streets can return None known_addresses = [ ("11", "Broadway", "New York", "NY", "11101"), ("32", "Broadway", "New-York", "NY", "11101"), 
("145", "Broadway", "New York", "NY", "11102"), ("360", "BROADWAY", "NEW YORK", "NY", "11102"), (“700, "Broadway", "New-York", "NY", "11104”), 
(“876, "Broadway", "New York", "NY", "11105”),]

There was a question about graph traversal, where each vertex has a cost.