gh-106318: Add example for str.isascii() (#137558)

Co-authored-by: Stan Ulbrych <[email protected]>
Co-authored-by: Hugo van Kemenade <[email protected]>

Author: 3 people

Doc/library/stdtypes.rst

@@ -2063,7 +2063,14 @@ expression support in the :mod:`re` module).
 
    Return ``True`` if the string is empty or all characters in the string are ASCII,
    ``False`` otherwise.
-   ASCII characters have code points in the range U+0000-U+007F.
+   ASCII characters have code points in the range U+0000-U+007F. For example:
+
+   .. doctest::
+
+      >>> 'ASCII characters'.isascii()
+      True
+      >>> 'µ'.isascii()
+      False
 
    .. versionadded:: 3.7