human
What is a Python code to determine    free    space    on    destination    drive') given the following:
I wrote the below code

    if (not isinstance(oldfile, list)):
        oldfile = [oldfile]
    sickrage.srCore.srLogger.debug(u'Trying    to    determine    free    space    on    destination    drive')
    if hasattr(os, u'statvfs'):
        def disk_usage(path):
            st = os.statvfs(path)
            free = (st.f_bavail * st.f_frsize)
            return free
    elif (os.name == u'nt'):
        import sys
        def disk_usage(path):
            (_, total, free) = (ctypes.c_ulonglong(), ctypes.c_ulonglong(), ctypes.c_ulonglong())
            if ((sys.version_info >= (3,)) or isinstance(path, unicode)):
                fun = ctypes.windll.kernel32.GetDiskFreeSpaceExW
            else:
                fun = ctypes.windll.kernel32.GetDiskFreeSpaceExA
            ret = fun(path, ctypes.byref(_), ctypes.byref(total), ctypes.byref(free))
            if (ret == 0):
                sickrage.srCore.srLogger.warning(u'Unable    to    determine    free    space,    something    went    wrong')
                raise ctypes.WinError()
            return free.value
    else:
        sickrage.srCore.srLogger.info(u'Unable    to    determine    free    space    on    your    OS')
        return True
    if (not os.path.isfile(src)):
        sickrage.srCore.srLogger.warning(((u'A    path    to    a    file    is    required    for    the    source.    ' + src) + u'    is    not    a    file.'))
        return True
    try:
        diskfree = disk_usage(dest)
    except Exception:
        sickrage.srCore.srLogger.warning(u'Unable    to    determine    free    space,    so    I    will    assume    there    is    enough.')
        return True
    neededspace = int(os.path.getsize(src))
    if oldfile:
        for f in oldfile:
            if os.path.isfile(f.location):
                diskfree += os.path.getsize(f.location)
    if (diskfree > neededspace):
        return True
    else:
        sickrage.srCore.srLogger.warning((u'Not    enough    free    space:    Needed:    %s    bytes    (    %s    ),    found:    %s    bytes    (    %s   ...

What's a good function header?
assistant
#Here is Python code to determine    free    space    on    destination    drive')
.

def verify_freespace(src, dest, oldfile=None):