python - How to map over a value iff it's distinct from None? -

is there concise way how map on value if , if it's not none? like

def fmapmaybe(f, v):     if v not none:         f(v)     else:         none 

update: i'm looking way how process values, if they're distinct none, , keep none otherwise, semantic fmapmaybe.

in above code, f arbitrary 1-argument function , v value should passed f iff it's distinct none. there no further restrictions on v or f are.

to give specific example: want string value dictionary , convert integer, if found. result should integer, or none. using above function, i'd write:

fmapmaybe(int, os.environ.get('lines')) 

is there shorter, more concise way?

this is, don stewart commented, analogous fmap on maybe functor in haskell, or map on option in scala. (and if consider f can return none, analogous monadic >>= in haskell , flatmap in scala.)

if don't tell v , want do, best can come with. if v iterable:

result = [f(x) x in v if x != none] 

if v single value if condition sound ok me.