code: func (t *TreeView) SetPrefixes(prefixes []string) *TreeView {
  	t.prefixes = prefixes
  	return t
  }
docs: // SetPrefixes defines the strings drawn before the nodes' texts. This is a
  // slice of strings where each element corresponds to a node's hierarchy level,
  // i.e. 0 for the root, 1 for the root's children, and so on (levels will
  // cycle).
  //
  // For example, to display a hierarchical list with bullet points:
  //
  //   treeView.SetGraphics(false).
  //     SetPrefixes([]string{"* ", "- ", "x "})