a = u"String" # Python 3.6 a = f"" a = F"" a = rf"" a = fr"" a = fu"" a = uf"" a = bf"" a = fb"" a = ufr"" # python 3.3 a = u"" a = r"" a = b"" a = rb"" a = br"" # python 3.2, 3.1 a = r"" a = b"" a = br"" # python 3.0 a = r"" a = b"" # python 2.7, 2.6 a = u"" a = r"" a = ur"" a = b"" a = br"" # python 2.5 a = u"" a = r"" a = ur"" # combined b = u"" b"" # never was available a = rr"" a = bb"" a = uu""