Checks if x is None. Handy with filtering functions:
remove(isnone, list_of_dirty_data)
Plays nice with silent(), which returns None on fail:
remove(isnone, imap(silent(int), strings_with_numbers))
Note that it’s usually simpler to use keep() or compact() if you don’t need to distinguish between None and other falsy values.
Checks if x is not None. A shortcut for complement(isnone) meant to be used when bool is not specific enough. Compare:
select_values(notnone, data_dict) # removes None values
compact(data_dict) # removes all falsy values
Increments its argument by 1.
Decrements its argument by 1.
Checks if x is even.
Checks if x is odd.