How to check if a Unix .tar.gz file is a valid file without uncompressing?

Question

I have found the question How to determine if data is valid tar file without a file?, but I was wondering: is there a ready made command line solution?

Answer 1

These are all very sub-optimal solutions. From the GZIP spec

ID2 (IDentification 2)
These have the fixed values ID1 = 31 (0x1f, \037), ID2 = 139 (0x8b, \213), to identify the file as being in gzip format.

Has to be coded into whatever language you're using.