return 0
+# from python2.7:subprocess.py
+def check_output(*popenargs, **kwargs):
+ r"""Run command with arguments and return its output as a byte string.
+
+ If the exit code was non-zero it raises a CalledProcessError. The
+ CalledProcessError object will have the return code in the returncode
+ attribute and output in the output attribute.
+
+ The arguments are the same as for the Popen constructor. Example:
+
+ >>> check_output(["ls", "-l", "/dev/null"])
+ 'crw-rw-rw- 1 root root 1, 3 Oct 18 2007 /dev/null\n'
+
+ The stdout argument is not allowed as it is used internally.
+ To capture standard error in the result, use stderr=STDOUT.
+
+ >>> check_output(["/bin/sh", "-c",
+ ... "ls -l non_existent_file ; exit 0"],
+ ... stderr=STDOUT)
+ 'ls: non_existent_file: No such file or directory\n'
+ """
+ if 'stdout' in kwargs:
+ raise ValueError('stdout argument not allowed, it will be overridden.')
+ process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
+ output, unused_err = process.communicate()
+ retcode = process.poll()
+ if retcode:
+ cmd = kwargs.get("args")
+ if cmd is None:
+ cmd = popenargs[0]
+ raise subprocess.CalledProcessError(retcode, cmd)
+ return output
+
+
def file_reader_method (missing_ok = False):
"""Decorator for simplifying reading of files.