Unzip the file (with path `filename`) to the destination `location`.  All
    files are written based on system defaults and umask (i.e. permissions are
    not preserved), except that regular file members with any execute
    permissions (user, group, or world) have "chmod +x" applied after being
    written. Note that for windows, any execute changes using os.chmod are
    no-ops per the python docs.

def unzip_file(filename, location, flatten=True):
    # type: (str, str, bool) -> None
    """
    Unzip the file (with path `filename`) to the destination `location`.  All
    files are written based on system defaults and umask (i.e. permissions are
    not preserved), except that regular file members with any execute
    permissions (user, group, or world) have "chmod +x" applied after being
    written. Note that for windows, any execute changes using os.chmod are
    no-ops per the python docs.
    """
    ensure_dir(location)
    zipfp = open(filename, 'rb')
    try:
        zip = zipfile.ZipFile(zipfp, allowZip64=True)
        leading = has_leading_dir(zip.namelist()) and flatten
        for info in zip.infolist():
            name = info.filename
            fn = name
            if leading:
                fn = split_leading_dir(name)[1]
            fn = os.path.join(location, fn)
            dir = os.path.dirname(fn)
            if fn.endswith('/') or fn.endswith('\\'):
                # A directory
                ensure_dir(fn)
            else:
                ensure_dir(dir)
                # Don't use read() to avoid allocating an arbitrarily large
                # chunk of memory for the file's content
                fp = zip.open(name)
                try:
                    with open(fn, 'wb') as destfp:
                        shutil.copyfileobj(fp, destfp)
                finally:
                    fp.close()
                    mode = info.external_attr >> 16
                    # if mode and regular file and any execute permissions for
                    # user/group/world?
                    if mode and stat.S_ISREG(mode) and mode & 0o111:
                        # make dest file have execute for user/group/world
                        # (chmod +x) no-op on windows per python docs
                        os.chmod(fn, (0o777 - current_umask() | 0o111))
    finally:
        zipfp.close()