def __getitem__(self, key):
        values = dict.__getitem__(self, key.lower())
        if len(values) == 1:
            return values[0]
        else:
            return ", ".join(values)
Add a request parser for a keyword.
dataset/ETHPy150Open w3c/wptserve/wptserve/request.py/RequestHeaders.__getitem__--crossover with--dataset/ETHPy150Open fp7-ofelia/ocf/expedient/src/python/expedient/common/middleware/threadlocals.py/add_parser