multi choice parameter values.
    :param parameters: the parameters tree.
    :param name: the name of the parameter.
    :param type_converter: function to convert the chosen value to a different type (e.g. str, float, int). default = 'str'
    :returns dictionary: value -> values

def multiChoiceParam(parameters, name, type_converter = str):
    """ multi choice parameter values.
    :param parameters: the parameters tree.
    :param name: the name of the parameter.
    :param type_converter: function to convert the chosen value to a different type (e.g. str, float, int). default = 'str'
    :returns dictionary: value -> values
    """
    param = parameters.find(".//MultiChoiceParam[@Name='{name}']".format(name=name))
    value = param.find('Value')
    values = param.find('Values')
    return [type_converter(values[int(item.text)].text) for item in value.findall('Item')]