https-proxy-agent/index.d.ts

declare module 'https-proxy-agent' {
    import * as https from 'https'

    namespace HttpsProxyAgent {
        interface HttpsProxyAgentOptions {
            host: string
            port: number | string
            secureProxy?: boolean
            headers?: {
                [key: string]: string
            }
            [key: string]: any
        }
    }
    
    // HttpsProxyAgent doesnt *actually* extend https.Agent, but for my purposes I want it to pretend that it does
    class HttpsProxyAgent extends https.Agent {
        constructor(opts: HttpsProxyAgent.HttpsProxyAgentOptions | string)
    }

    export = HttpsProxyAgent
}