How to have multi values in parameters

[BrianLewis]

Is there a way on the parameter to have multiple values in one go as shown in my example below? 

Selecting just A only or B only makes sense, but how could I have a selection in the Parameter that takes both A and B at the same time?

parameter: xxxx_param {
group_label: "Parameter Selections"
label: "xxxx Selection"
description: ""
type: string

allowed_value: {
label: "A"
value: "A"
}

allowed_value: {
label: "B"
value: "B"
}

allowed_value: {
label: "All"
value: "A" and "B"
}

[Francesco_V]

Right now parameters do not allow you to select multiple options. 

[karthikv606]

Is there a work around for this?