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### Conditionals

The if and else statements can perform simple tests. Here’s an example:

```# Compute the maximum (z) of a and b
if a < b:
z = b
else:
z = a```

The bodies of the if and else clauses are denoted by indentation. The else clause is optional.

To create an empty clause, use the pass statement as follows:

```if a < b:
pass      # Do nothing
else:
z = a```

You can form Boolean expressions by using the or, and, and not keywords:

```if b >= a and b <= c:
print "b is between a and c"
if not (b < a or b > c):
print "b is still between a and c"```

To handle multiple-test cases, use the elif statement, like this:

```if a == '+':
op = PLUS
elif a == '-':
op = MINUS
elif a == '*':
op = MULTIPLY
else:
raise RuntimeError, "Unknown operator"```

To denote truth values, you ...

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