def check_extras(dist, attr, value):
    try:
        for k,v in value.items():
            list(pkg_resources.parse_requirements(v))
    except (TypeError,ValueError,AttributeError):
        raise DistutilsSetupError(
            "'extras_require' must be a dictionary whose values are "
            "strings or lists of strings containing valid project/version "
            "requirement specifiers."
        )
Verify that extras_require mapping is valid
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/setuptools-0.6c11/setuptools/dist.py/check_extras