setContextProvider(customColumnContextProvider) {
        this.gate.customColumnContextProvider = customColumnContextProvider;
        this.gate.isContextTemporary = true;
        return this;
    }
Specifies a function for retrieving the context provided by a gate to other gates.
@param {!function(qubit:!int,gate:!Gate):!Array.<!{key: !string, val: *}>} customColumnContextProvider
@returns {!GateBuilder}