How to use the ethereum-types.AbiType.Event function in ethereum-types

_.map(abiArray, (abi: AbiDefinition) => {
            switch (abi.type) {
                case AbiType.Event:
                    // tslint:disable-next-line:no-unnecessary-type-assertion
                    this._addEventABI(abi as EventAbi, ethersInterface);
                    break;

                case AbiType.Function:
                    // tslint:disable-next-line:no-unnecessary-type-assertion
                    this._addMethodABI(abi as MethodAbi, contractName);
                    break;

                default:
                    // ignore other types
                    break;
            }
        });
    }

_.map(abiArray, (abi: AbiDefinition) => {
            if (abi.type === AbiType.Event) {
                const topic = ethersInterface.events[abi.name].topics[0];
                this._methodIds[topic] = abi;
            }
        });
    }