**✓ Boolean Expressions**

>>> 5 == 5 True >>> 5 == 6 False> >> type(True) <type 'bool'> >>> type(False) <type 'bool'>

**✓ Relational operators**

```
x != y
x > y
x < y x >= y
x <= y
```

**✓ Logical Operators** – There are three logical operators: and, or, and not.

```
n%2 == 0 or n%3 == 0 true if either of the conditions is true
>>> 6 and True # Any nonzero number is interpreted as true
True
```

**✓ Conditional execution**

```
if x < y: print 'x is less than y' elif x > y:
print 'x is greater than y'
else:
print 'x and y are equal'
```

**✓ Nested conditionals**

```
if 0 < x:
if x < 10:
print 'x is a positive single-digit number.'
```

**✓ Recursion** – It is legal for one function to call another, and it is also legal for a function to call itself.

```
def countdown(n):
if n <= 0:
print 'Blastoff!'
else:
print n
countdown(n-1)
```

**✓ Keyboard Input**

```
>>> prompt = 'What...is the airspeed velocity of an unladen swallow?\n'
>>> speed = raw_input(prompt)
What...is the airspeed velocity of an unladen swallow?
17
>>> int(speed)
17
```

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