The keys() method of dict objects behaves differently under Python 2 and Python 3. In 2.x keys() returns a copy of all keys as list, in 3 it returns a view (iterator without a copy). Modernize converts {{{dict.keys()}}} to {{{list(dict.keys())}}} to get the same behavior. This is inefficient, inelegant and (in most cases) not needed.

In most cases keys() can be removed

for loop

for key in somedict.keys():
    ...

equals:

for key in somedict:
    ...

EXCEPTION: a copy is still required when the for-loop body adds or removes entries from somedict.

contains check

if item in somedict.keys():
    ...

equals

if item in somedict:
    ...

NOTE: with keys(), the code is O(n). without it is O(1).

set, string join, list, sorted list

set(somedict.keys()) == set(somedict)



''.join(somedict.keys()) == ''.join(somedict)



keys = somedict.keys()

equals:

keys = list(somedict)



keys = somedict.keys()
keys = keys.sort()

equals:

keys = sorted(somedict)