Storing Subprocess Results

[topazcode]

I am using the subprocess module to run some shell commands on a Linux
system:

import subprocess
output = subprocess.call('''ssh server1 "uptime"''', shell=True)

The above assigns the output variable with a return code, i.e. 0 in
this case.  How can I actually capture the data returned from
subprocess.call, rather than just the return code?  I'd like to have
the output variable contain the uptime string in this case.  Any help
is appreciated.  Thanks.