@classmethod
    def set_policy_from_env(cls):
        envmap = {
            "IGNORE": False,
            "FALSE": False,
            "SAVE": True,
            "TRUE": True,
            "VERBOSE": "VERBOSE",
            "DEFAULT": "VERBOSE",
        }
        oldvalue = cls.DEFAULT_H5_BACKTRACE_POLICY
        envvalue = os.environ.get("PT_DEFAULT_H5_BACKTRACE_POLICY", "DEFAULT")
        try:
            newvalue = envmap[envvalue.upper()]
        except __HOLE__:
            warnings.warn("Invalid value for the environment variable "
                          "'PT_DEFAULT_H5_BACKTRACE_POLICY'.  The default "
                          "policy for HDF5 back trace management in PyTables "
                          "will be: '%s'" % oldvalue)
        else:
            cls.DEFAULT_H5_BACKTRACE_POLICY = newvalue

        return oldvalue
dataset/ETHPy150Open PyTables/PyTables/tables/exceptions.py/HDF5ExtError.set_policy_from_env