Construct a safe builtin environment without I/O functions.

    :rtype: dict

def _safebuiltins():
    """Construct a safe builtin environment without I/O functions.

    :rtype: dict"""

    result = {}

    objectnames = [
        objectname for objectname in dir(builtins)
        if objectname not in BUILTIN_IO_PROPS
    ]

    for objectname in objectnames:
        result[objectname] = getattr(builtins, objectname)

    return result