write a function
get_direction(start, end) that returns the end station that is in the direction of travel between the start and end , or None if the start and end is not on the same line.
use python
Extracted text: Boston Subway The Boston Subway e has four different colored trains, some of which have multiple routes. We have simplified the routes so that each train has a single route with the following stations (in order from north to south) and that each colored line intersects with another colored line at exactly one station. • Red Line: Alewife, Davis, Porter, Harvard, Central, Kendall/MIT, Charles/MGH, Downtown Crossing, South Station, Broadway, Andrew, JFK/UMass • Orange Line: Oak Grove, Malden Center, Wellington, Assembly, Sullivan Square, Community College, North Station, Haymarket, State, Downtown Crossing, Chinatown, Tufts Medical Center, Back Bay, Mass Avenue, Ruggles, Roxbury Crossing, Jackson Square, Stony Brook, Green Street, Forest Hills • Blue Line: Wonderland, Revere Beach, Beachmont, Suffolk Downs, Orient Heights, Wood Island, Airport, Maverick, Aquarium, State • Green Line: Haymarket, Government Center, Park Street, Boylston, Arlington, Copley, Haynes Convention Center, Kenmore, Blandford Street, Boston University East, Boston University Central, Boston University West, Saint Paul Street, Pleasant Street, Babcock Street, Packards Corner, Harvard Avenue, Griggs Street, Allston Street, Warren Street, Washington Street, Sutherland Road, Chiswick Road, Chestnut Hill Avenue, South Street, Boston College Station names must match exactly (unforgiving about upper/lowercase and abbreviations) with the exception of names that have a "/" in them. These stations can be referred to be either one. For example, both "Kendall" and "MIT" refer to the same station. Note: The simplification of our train lines is such that each line intersects with other lines in exactly one station. But not all lines intersect every other line.