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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def index(credentials = None):
 """Get list of projects or shortcut to other functionality"""


    #handle shortcut
    shortcutresponse = entryshortcut(credentials)
    if shortcutresponse is not None:
        return shortcutresponse

    projects = []
    user, oauth_access_token = parsecredentials(credentials)
    totalsize = 0.0
    if settings.LISTPROJECTS:
        projects, totalsize = getprojects(user)

    errors = "no"
    errormsg = ""

    corpora = CLAMService.corpusindex()

    #pylint: disable=bad-continuation
    return withheaders(flask.make_response(flask.render_template('response.xml',
            version=VERSION,
            system_id=settings.SYSTEM_ID,
            system_name=settings.SYSTEM_NAME,
            system_description=settings.SYSTEM_DESCRIPTION,
            system_author=settings.SYSTEM_AUTHOR,
            system_version=settings.SYSTEM_VERSION,
            system_email=settings.SYSTEM_EMAIL,
            user=user,
            project=None,
            url=getrooturl(),
            statuscode=-1,
            statusmessage="",
            statuslog=[],
            completion=0,
            errors=errors,
            errormsg=errormsg,
            parameterdata=settings.PARAMETERS,
            inputsources=corpora,
            outputpaths=None,
            inputpaths=None,
            profiles=settings.PROFILES,
            datafile=None,
            projects=projects,
            totalsize=totalsize,
            actions=settings.ACTIONS,
            disableinterface=not settings.ENABLEWEBAPP,
            info=False,
            accesstoken=None,
            interfaceoptions=settings.INTERFACEOPTIONS,
            customhtml=settings.CUSTOMHTML_INDEX,
            allow_origin=settings.ALLOW_ORIGIN,
            oauth_access_token=oauth_encrypt(oauth_access_token),
            auth_type=auth_type()
            )), headers={'allow_origin':settings.ALLOW_ORIGIN})