def METHOD_NAME(self, min_length):
    """
    Sets the minimum length of the type.
    May only be used to increase the minimum length. May not be called if
    an exact length has been set.
    """
    if self._length:
        raise CompilerPanic("Type already has a fixed length")
    if self._min_length > min_length:
        raise CompilerPanic("Cannot reduce the min_length of ArrayValueType")
    self._min_length = min_length