A Boolean expression is an expression that has the value True or False. Some common operators that yield conditional expressions are as follow:
- Equal: ==
- Not equal: !=
- Strictly less, less or equal: <, <=
- Strictly greater, greater or equal: >, >=
You combine different Boolean values with or and and. The keyword not gives the logical negation of the expression that follows. Comparisons can be chained so that, for example, x < y < z is equivalent to x < y and y < z. The difference is that y is only evaluated once in the first example. In both cases, z is not evaluated at all when the first condition, x < y, evaluates to False:
2 >= 4 # False
2 < 3 < 4 # True
2 < 3 and 3 < 2 # False
2 != 3 < 4 or False # True
2 <= 2 and 2 >= 2 # True
not 2 == 3 # True...
