Exporting BasePlugin from @cloudant/cloudant

cloudant.js

// Add this import after requiring ('./lib/client.js')
const BasePlugin = require('./plugins/base.js');

// This adds BasePlugin to the existing export
Cloudant.BasePlugin = BasePlugin;

...

// change nano.basePlugin = require('./plugins/base.js'); to
nano.basePlugin = BasePlugin;

index.d.ts

// Add the following to the cloudant namespace

    interface PluginConfig {}
    interface PluginState {
        maxAttempt: number;
    }

    type PluginCallbackFunction = (state: PluginState) => void;
    type PluginLifecycleFunction = (state: PluginState, event: any, callback: PluginCallbackFunction) => void;

    export class BasePlugin {
        public static pluginVersion: number; 
        public disabled: boolean;
        public _cfg: PluginConfig;
        public constructor(client: nano.DocumentScope<{}>, config?: PluginConfig)
        public get id(): string
        // Having a more specific type for `request` would be nice too
        public onRequest(state: PluginState, request: any, callback: PluginLifecycleFunction)
        // Having a more specific type for `response` would be nice too
        public onResponse(state: PluginState, response: any, callback: PluginLifecycleFunction)
        // Having a more specific type for `error` would be nice too (could this be `error: Error`?)
        public onError(state: PluginState, error: any, callback: PluginLifecycleFunction)
    }