lodash map

const _quote_filter = _.map(quote_state, (val, key) => {   if (val) {      return key   }})console.log(_quote_filter) //=> [ 'btc', undefined, undefined ]_.each(markets, (obj, key) => {   obj.symbol = key})console.log(markets)//=> {       'BTC/USD': { buys: 0, sells: 3, symbol: 'BTC/USD' },       'DASH/BTC': { buys: 3, sells: 1, symbol: 'DASH/BTC' },       'ETH/BTC': { buys: 3, sells: 2, symbol: 'ETH/BTC' }    }