How to trim leading and trailing white-spaces by a single command?

Question

Supposing you have a string value in a variable STRING, how can you remove leading and trailing whitespaces with a single command (line)?

For instance, the

Answer 1

Concerning leading whitespaces only, the following code works (_ means TAB):

set "STRING=  two spaces, trimmed text string, space-tab-space _ "

rem no "delims=" option given, so defaulting to spaces and tabs:
for /F "tokens=* eol= " %%S in ("%STRING%") do set "LEFTTRIMMED=%%S"

echo "%LEFTTRIMMED%"

However, the trailing whitespaces are still present; but they can removed by the approaches shown in this thread.