import ast, os

libdir = 'C:/programs/Python35/Lib'
dirs = [libdir]
for item in os.scandir(libdir):
    if item.is_dir():
        dirs.append(os.path.join(libdir, item.name))
for dir in dirs:
    os.chdir(dir)
    for fname in os.listdir(dir):
        if fname.endswith('.py'):
            with open(fname, encoding='utf-8') as f:
                try:
                    src = f.read()
                except UnicodeDecodeError:
                    pass
                try:
                    compile(ast.parse(src), fname, 'exec')
                except (SyntaxError, Exception) as e:
                    if not fname.startswith('bad'):
                        print(dir, fname, e)