gateAtLocIsDisabledReason(col, row) {
        if (col < 0 || row < 0 || col >= this._colRowDisabledReason.length || row >= this.numWires) {
            return undefined;
        }
        return this._colRowDisabledReason[col][row];
    }
@param {!int} col
@param {!int} row
@returns {undefined|!string}