Lookup processor class object by its name

def lookupProcessor(name):
    """Lookup processor class object by its name"""
    if name in _proc_lookup:
        return _proc_lookup[name]
    else:
        error_string = 'If you are creating a new processor, please read the\
documentation on creating a new processor'
        raise LookupError("Unknown processor %s\n%s" % (name, error_string))