filter and map / deprecated?

[Matt Gerrans]

Also, I suppose if you were *really* in a rush and wanted to get old code
working, then all you'd have to do is add something like this to it:

def map( func, seq ):  return [ func(x) for x in seq ]
def filter( func, seq ):  return [ x for x in seq if func(x) ]

This will probably be less efficient than Serge's solution.   It is probably
also better to have that self-documenting "from legacy ..." in there, to
boot.

I think after a using list comprehensions for a while, they become a lot
more comfortable though, so it is not such a bad thing to develop the habit
of using them instead.   Then, in the fullness of time, map() and filter()
will begin to look funny.