code: func (c *Container) runToBitmap() {
  	statsHit("runToBitmap")
  	runs := c.runs()
  	bitmap := make([]uint64, bitmapN)
  	c.typ = containerBitmap
  	c.setBitmap(bitmap)
  
  	c.mapped = false
  
  	// return early if empty
  	if c.n == 0 {
  		return
  	}
  
  	for _, r := range runs {
  		// TODO this can be ~64x faster for long runs by setting maxBitmap instead of single bits
  		//note v must be int or will overflow
  		for v := int(r.start); v <= int(r.last); v++ {
  			bitmap[v/64] |= (uint64(1) << uint(v%64))
  		}
  	}
  }
docs: // runToBitmap converts from RLE format to bitmap format.