<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def all_editable_exts():

 """Return a list of all editable extensions"""

    exts = []
    for (language, extensions) in languages.ALL_LANGUAGES.items():
        exts.extend(list(extensions))
    return ['.' + ext for ext in exts]