human
Can you provide a Python program to print >>sys given the following:
I wrote the below code

    if (not os.path.isdir('a')):
        print >>sys.stderr, 'error:    comparison    feature    not    initialized'
        sys.exit(4)
    print ('=' * 80)
    print 'WERKZEUG    INTERNAL    BENCHMARK    --    COMPARE    MODE'.center(80)
    print ('-' * 80)
    def _error(msg):
        print >>sys.stderr, 'error:', msg
        sys.exit(1)
    def _hg_update(repo, node):
        hg = (lambda *x: subprocess.call((['hg'] + list(x)), cwd=repo, stdout=null_out, stderr=null_out))
        hg('revert', '-a', '--no-backup')
        client = subprocess.Popen(['hg', 'status', '--unknown', '-n', '-0'], stdout=subprocess.PIPE, cwd=repo)
        unknown = client.communicate()[0]
        if unknown:
            client = subprocess.Popen(['xargs', '-0', 'rm', '-f'], cwd=repo, stdout=null_out, stdin=subprocess.PIPE)
            client.communicate(unknown)
        hg('pull', '../..')
        hg('update', node)
        if (node == 'tip'):
            diff = subprocess.Popen(['hg', 'diff'], cwd='..', stdout=subprocess.PIPE).communicate()[0]
            if diff:
                client = subprocess.Popen(['hg', 'import', '--no-commit', '-'], cwd=repo, stdout=null_out, stdin=subprocess.PIPE)
                client.communicate(diff)
    _hg_update('a', node1)
    _hg_update('b', node2)
    d1 = run('a', no_header=True)
    d2 = run('b', no_header=True)
    print 'DIRECT    COMPARISON'.center(80)
    print ('-' * 80)
    for key in sorted(d1):
        delta = (d1[key] - d2[key])
        if ((abs((1 - (d1[key] / d2[key]))) < TOLERANCE) or (abs(delta) < MIN_RESOLUTION)):
            delta = '=='
        else:
            delta = ('%+.4f    (%+d%%)' % (delta, round((((d2[key] / d1[key]) * 100) - 100))))
        print ('%36s            %.4f                %.4f                %s' % (format_func(key), d1[key], d2[key], delta))
    print ('-' * 80)

What's a good function header?
assistant
#Here is Python program to print >>sys.

def compare(node1, node2):