Does anybody have an example of successful implementation of setRangeFills()?

I rewrote my code snippet separately, and it worked fine.

let refText = figma.currentPage.findOne(n => n.name === "Testing...") as TextNode
let styles = refText.getStyledTextSegments(['fills'])

let subject = figma.currentPage.selection[0] as TextNode
for (let style = 0; style < styles.length; style++) {
  const object = styles[style]
  subject.setRangeFills(object.start, object.end, object.fills)
}

figma.closePlugin()

Now I will compare and see what mistake I am making. Thanks for the help, @tank666