code: function reduceJSON(accum, json, fn, searchFor) {
    if (isKey(json, searchFor)) {
      return fn(accum, json[searchFor]);
    } else if (isAtom(json)) {
      return accum;
    } else if (isArray(json)) {
      return json.reduce((acc, item) => {
        return reduceJSON(acc, item, fn, searchFor);
      }, accum);
    } else {
      const keys = Object.keys(json);
  
      return keys.reduce((acc, key) => {
        return reduceJSON(acc, json[key], fn, searchFor);
      }, accum);
    }
  }
docs: /* applies function to value at given key