[Python-3000] Support for PEP 3131

[Stephen J. Turnbull]

Collin Winter writes:

 > Sincere question: if these characters aren't needed, why are they
 > provided?

I already gave a long jargony answer, but maybe this analogy is
better:

Most of the time automatic line-wrapping gives excellent results, but
sometimes you need the newline character to achieve special effects
(eg, poetry).  Directional controls are similar: used for "special
effects" that are none-the-less an everyday part of the language.

 > From what I can tell by googling, they're needed when, e.g.,
 > Arabic is embedded in an otherwise left-to-right script.

No, they are unnecessary; there are algorithms that do a fine job --
for most purposes, but not all.  It's the exceptions where the control
characters are needed.

The Unicode technical committee does not think identifiers are
exceptional, and they are experts (including Hebrew and Arabic native
speakers, I am sure).