[challenge]Transforming a list

Question

Given a list
points = [[1,"a","b"],[2,"d","e"],[3,"e","f"]]

transfer to

[[1,'a,b'],[2,'b,c'],[3,'c,d']]

oneliner welcome

Answer 1

Edit:
print([[i[0],','.join(i[1:])] for i in points]) #this makes sense

print([[i[0],','.join([chr(ord('a')+i[0]-1),chr(ord('a')+i[0])])] for i in points]) #but this answers the question
https://code.sololearn.com/cUWnW042xht6/?ref=app

Answer 2

wht to do??
not clear...