def wep_to_value(scale_value):
    """
    This method will transform a string value from the WEP scale to its
    confidence integer representation.

    The scale for this confidence representation is the following:

    .. list-table:: WEP to STIX Confidence
        :header-rows: 1

        * - WEP
          - STIX Confidence Value
        * - Impossible
          - 0
        * - Highly Unlikely/Almost Certainly Not
          - 10
        * - Unlikely/Probably Not
          - 20
        * - Even Chance
          - 50
        * - Likely/Probable
          - 70
        * - Highly likely/Almost Certain
          - 90
        * - Certain
          - 100

    Args:
        scale_value (str): A string value from the scale. Accepted strings are
            "Impossible", "Highly Unlikely/Almost Certainly Not",
            "Unlikely/Probably Not", "Even Chance", "Likely/Probable",
            "Highly likely/Almost Certain" and "Certain". Argument is case
            sensitive.

    Returns:
        int: The numerical representation corresponding to values in the WEP
            scale.

    Raises:
        ValueError: If `scale_value` is not within the accepted strings.

    """
    if scale_value == 'Impossible':
        return 0
    elif scale_value == 'Highly Unlikely/Almost Certainly Not':
        return 10
    elif scale_value == 'Unlikely/Probably Not':
        return 30
    elif scale_value == 'Even Chance':
        return 50
    elif scale_value == 'Likely/Probable':
        return 70
    elif scale_value == 'Highly likely/Almost Certain':
        return 90
    elif scale_value == 'Certain':
        return 100
    else:
        raise ValueError("STIX Confidence value cannot be determined for %s" % scale_value)