<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def parse_extras(extras_str):
 # type: (AnyStr) -> List[AnyStr] """ Turn a string of extras into a parsed extras list """


    from pkg_resources import Requirement

    extras = Requirement.parse("fakepkg{0}".format(extras_to_string(extras_str))).extras
    return sorted(dedup([extra.lower() for extra in extras]))