function storeSegment(obj, segment) {
  if (obj) {
    obj[symbols.segment] = segment || this.getSegment()
  }
}
Associates a segment with the given object.

- `storeSegment(obj [, segment])`

If no segment is provided, the currently active segment is used.

@memberof Shim.prototype
@param {!*}            obj       - The object to retrieve a segment from.
@param {TraceSegment}  [segment] - The segment to link the object to.