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Conditionals

The if and else statements can perform simple tests. For 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"
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