Python: Predicates

The is_infant() function is a predicate or question function. A predicate answers a “yes or no” question by returning a boolean value Predicates usually have handy names in every language to make them easy to analyze. In Python, predicates begin with the prefix is, are, or has:

• is_infant() — "is it a baby?"
• has_children() — "are there children?"
• is_empty() — "is it empty?"
• has_errors() — "are there mistakes?"

A function is considered a predicate if it returns the boolean values True or False.

Let's write another predicate function. It takes a string and checks if it is the word 'Castle':

def is_castle(string):
    return string == 'Castle'

print(is_castle('Sea')) # False

Instructions

Write a function is_mister() that accepts a string and checks if it is the word 'Mister'.

is_mister('Mister') # True
is_mister('Missis') # False

Tips

• Naming in Programming

Definitions

• Predicate выражение, отвечающее на вопрос «да» или «нет» с помощью типа bool.