feat(PrintErr): add method for printing to error output

streams.go

@@ -1,5 +1,5 @@
 // Package ioes or "in, out, error streams" provides standard names and utilities
-// for working with traditional "stdout" streams
+// for working with traditional stdin/stdout/stderr streams.
 package ioes
 
 import (
@@ -55,7 +55,7 @@ func (s IOStreams) Close() error {
 	return nil
 }
 
-// Print writes a msg to the Out stream
+// Print writes a msg to the out stream, printing
 func (s IOStreams) Print(msg string) {
 	if s.SpinnerActive() {
 		s.StopSpinner()
@@ -64,6 +64,15 @@ func (s IOStreams) Print(msg string) {
 	s.Out.Write([]byte(msg))
 }
 
+// PrintErr writes a msg to the Err stream, printing
+func (s IOStreams) PrintErr(msg string) {
+	if s.SpinnerActive() {
+		s.StopSpinner()
+		defer s.StartSpinner()
+	}
+	s.ErrOut.Write([]byte(msg))
+}
+
 // NewIOStreams creates streams
 func NewIOStreams(in io.Reader, out, errOut io.Writer) IOStreams {
 	sp := spinner.New(spinner.CharSets[24], 100*time.Millisecond)