def import_string(import_name):
    """Imports an object based on a string.  This is useful if you want to
    use import paths as endpoints or something similar.  An import path can
    be specified either in dotted notation (``xml.sax.saxutils.escape``)
    or with a colon as object delimiter (``xml.sax.saxutils:escape``).

    If the `silent` is True the return value will be `None` if the import
    fails.

    :return: imported object
    """
    try:
        if ':' in import_name:
            module, obj = import_name.split(':', 1)
        elif '.' in import_name:
            items = import_name.split('.')
            module = '.'.join(items[:-1])
            obj = items[-1]
        else:
            return __import__(import_name)
        return getattr(__import__(module, None, None, [obj]), obj)
    except (ImportError, AttributeError):
        raise
