def is_valid_urn_string(instr):
    '''Could this string be part of a URN'''
    if instr is None or not isinstance(instr, str):
        return False
    #No whitespace
    # no # or ? or /
    if re.search("[\s|\?\/\#]", instr) is None:
        return True
    return False

# Note that this is not sufficient but it is necessary
dataset/ETHPy150Open fp7-ofelia/ocf/ofam/src/src/ext/geni/util/urn_util.py/is_valid_urn_string/original