ZPT Basics (part 2) - If It's Thursday, It Must be Italy
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ZPT also lets you "nest" conditional statements. For example, this is perfectly valid ZPT code:

---

<span tal:define="global day string:Thursday; global time string:12; global place string:Italy"></span> <span tal:condition="python:day == 'Thursday'"> <span tal:condition="python:time == '12'"> <span tal:condition="python:place == 'Italy'"> How about some pasta for lunch? </span> </span> </span>

---

I'm sure you'll agree, though, that this is both complex and frightening. And so, in addition to the comparison operators I've used so liberally thus far, Python also provides the "and", "or" and "not" logical operators which allow you to group conditional expressions together. The following table should make this clearer.

Assume delta = 12, gamma = 12 and omega = 9

Expression                          Evaluates To
------------------------------------------------------------------------
--

delta == gamma and delta > omega    True

delta == gamma and delta < omega    False

delta == gamma or delta < omega     True

delta > gamma or delta < omega      False

not delta                           False

Given this knowledge, it's a simple matter to rewrite the example above in terms of logical operators:

<span tal:define="global day string:Thursday; global time string:12;
global place string:Italy"></span>

<span tal:condition="python:day == 'Thursday' and time == '12' and place
== 'Italy'">
                How about some pasta for lunch?

</span>

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