oneNormalizedVariable (variableName) {
        var indexKey = this._postman_listIndexKey, // `key` for Variable
            variable = this.reference[variableName],
            i;

        if (variable && !variable.disabled) {
            return variable;
        }

        // traverse the members list in reverse direction in order to find the last enabled
        for (i = this.members.length - 1; i >= 0; i--) {
            variable = this.members[i];
            if (variable[indexKey] === variableName && !variable.disabled) {
                // update the input variable reference if comparison is not disabled
                this.reference[variableName] = variable;
                break; // return updated reference variable
            }
        }

        return this.reference[variableName];
    }
Fetches a variable and normalize its reference if disabled.
This updates the disabled variable `reference` in VariableList with its
last enabled duplicate(if found) in the `members` list.

@private
@param {String} variableName - The name of the variable to get
@returns {Variable} - In case of duplicates, returns last enabled