Unable to uncompressed RINEX .Z file

I am unable to uncompress rinex .Z file using any of the module available on python. The commone error I get is " ValueError: Bad header." or “error: Error -3 while decompressing data: incorrect header check”
The sample files can be accessed from
ftp://data-out.unavco.org/pub/rinex/obs/1994/299/

The module I tried are
unlzw3
shutil
zlib

My codes are as following

	str_object1 = open('abmf3240.19o.Z', 'rb').read()
	zlib.decompress(str_object1)


another code:
for file in glob.glob (’*.Z’):
file
unlzw3.unlzw(file)

last code that I tried is :

	str_object1 = open('abmf3240.19o.Z', 'rb').read()
	zlib.decompress(str_object1)