def _calculate_development_risk(module):
    """
    Function to calculate Software risk due to the development environment.
    This function uses the results of RL-TR-92-52, Worksheet 1B to
    determine the relative risk level.  The percentage of development
    environment characteristics (Dc) applicable to the system under
    development determine the risk level.

        Baseline (medium) development risk (D) is assigned a 1.
        Low development risk (Dc > 0.9) is assigned a 0.5.
        High development risk (Dc < 0.5) is assigned a 2.

    :param module: the :py:class:`rtk.software.CSCI.Model` or
                   :py:class:`rtk.software.Unit.Model` data model to calculate.
    :return: False if successful or True if an error is encountered.
    :rtype: bool
    """

    module.dc = sum(module.lst_development) / 43.0
    if module.dc < 0.5:                     # High risk
        module.d_risk = 2.0
    elif module.dc > 0.9:                   # Low risk
        module.d_risk = 0.5
    else:
        module.d_risk = 1.0

    return False