2 

     2 

     3 

     3 

     4 // first test 

     4 // first test 

     5 

     5 

     6 val ls1_urban = List(("1", "a"), ("2", "a"), ("1", "c"), ("2", "a"), ("1", "c"))

     6 val ls1_urban = List(("1", "a"), ("2", "a"), ("1", "c"), ("2", "a"), ("1", "c"))