let o = {a:1,b:2,c:3};
let k = ["b","c"];
let a = {};
for(let prop in o){
  if(k.includes(prop)){
    a[prop] = o[prop];
  }
}
< 3
> a
< Object { b: 2, c: 3 }

constructor(Value, {Writeable = true} = opts) {
    Object.assign(this, opts);
}

keep = (x, k) => Object.assign.apply({},[{}].concat(Object.keys(x).filter(t => k.includes(t)).map(t => {let obj = {}; obj[t] = x[t]; return obj; })))

encode =: */@(p:@i.@#^])
decode =: +/"1@=@q:

	def __gt__(self, other):            # this is why I hate python.
		return self.value > other

	def __lt__(self, other):
		return self.value < other

	def __eq__(self, other):
		return self.value == other

	def __ne__(self, other):
		return not(self == other)

	def __ge__(self, other):
		return not(self < other)

	def __le__(self, other):
		return not(self > other)

   ip =: 180*-&2
   ip 5
540