check environment for key/value pair

    Args:
        section_name (str): section name
        key_name (str): key to look up
        envname_pad (str): namespace padding
        logger (:obj:`logging.logger`): logging handle

    Returns:
        str: value in environment

def get_value_from_environment(
        section_name,
        key_name,
        envname_pad=ENVNAME_PAD,
        logger=logging.getLogger('ProsperCommon'),
):
    """check environment for key/value pair

    Args:
        section_name (str): section name
        key_name (str): key to look up
        envname_pad (str): namespace padding
        logger (:obj:`logging.logger`): logging handle

    Returns:
        str: value in environment

    """
    var_name = '{pad}_{section}__{key}'.format(
        pad=envname_pad,
        section=section_name,
        key=key_name
    )

    logger.debug('var_name=%s', var_name)
    value = getenv(var_name)
    logger.debug('env value=%s', value)

    return value