How to use the common.debug function in common

def find_framework_root():
    # XXX: find it from environment (FrameworkDir)
    try:
        froot = read_reg(_FRAMEWORKDIR_HKEY_ROOT)
        debug("Found framework install root in registry: %s" % froot)
    except WindowsError, e:
        debug("Could not read reg key %s" % _FRAMEWORKDIR_HKEY_ROOT)
        return None

    if not os.path.exists(froot):
        debug("%s not found on fs" % froot)
        return None

    return froot

def find_framework_root():
    # XXX: find it from environment (FrameworkDir)
    try:
        froot = read_reg(_FRAMEWORKDIR_HKEY_ROOT)
        debug("Found framework install root in registry: %s" % froot)
    except WindowsError, e:
        debug("Could not read reg key %s" % _FRAMEWORKDIR_HKEY_ROOT)
        return None

    if not os.path.exists(froot):
        debug("%s not found on fs" % froot)
        return None

    return froot

def find_batch_file(self):
        vs_dir = self.get_vs_dir()
        if not vs_dir:
            debug('find_executable():  no vs_dir')
            return None
        batch_file = os.path.join(vs_dir, self.batch_file_path)
        batch_file = os.path.normpath(batch_file)
        if not os.path.isfile(batch_file):
            debug('find_batch_file():  %s not on file system' % batch_file)
            return None
        return batch_file

def find_framework_root():
    # XXX: find it from environment (FrameworkDir)
    try:
        froot = read_reg(_FRAMEWORKDIR_HKEY_ROOT)
        debug("Found framework install root in registry: %s" % froot)
    except SCons.Util.WinError, e:
        debug("Could not read reg key %s" % _FRAMEWORKDIR_HKEY_ROOT)
        return None

    if not os.path.exists(froot):
        debug("%s not found on fs" % froot)
        return None

    return froot

def get_installed_visual_studios():
    global InstalledVSList
    global InstalledVSMap
    if InstalledVSList is None:
        InstalledVSList = []
        InstalledVSMap = {}
        for vs in SupportedVSList:
            debug('trying to find VS %s' % vs.version)
            if vs.get_executable():
                debug('found VS %s' % vs.version)
                InstalledVSList.append(vs)
                InstalledVSMap[vs.version] = vs
    return InstalledVSList

def get_installed_visual_studios():
    global InstalledVSList
    global InstalledVSMap
    if InstalledVSList is None:
        InstalledVSList = []
        InstalledVSMap = {}
        for vs in SupportedVSList:
            debug('trying to find VS %s' % vs.version)
            if vs.get_executable():
                debug('found VS %s' % vs.version)
                InstalledVSList.append(vs)
                InstalledVSMap[vs.version] = vs
    return InstalledVSList

def find_batch_file(self):
        vs_dir = self.get_vs_dir()
        if not vs_dir:
            debug('find_executable():  no vs_dir')
            return None
        batch_file = os.path.join(vs_dir, self.batch_file_path)
        batch_file = os.path.normpath(batch_file)
        if not os.path.isfile(batch_file):
            debug('find_batch_file():  %s not on file system' % batch_file)
            return None
        return batch_file

def test_ping(info):
    debug('Running ping test')
    vms = info['vms']
    vm_credentials = get_vm_credentials()
    for vm in sorted(vms.keys()):
        vms[vm]['qrouter'] = get_vm_qrouters(info, vm)

    vm_pairs = list(combinations(sorted(vms.keys()), 2))
    pprint.pprint(vm_pairs)
    cmds = {}
    for (src_vm, dst_vm) in vm_pairs:
        for qrouter in vms[src_vm]['qrouter']:
            debug(qrouter)
            if not cmds.has_key(qrouter):
                cmds[qrouter] = {}
            cmds[qrouter][(src_vm, dst_vm)] = {}
            for src_ip in vms[src_vm]['interfaces'].keys():
                if is_network_public(src_ip, src_vm, info):