Python: The construct else + if = elif

The function get_type_of_sentence() only distinguishes between question and normal sentences. Let's add support for exclamatory sentences to it:

def get_type_of_sentence(sentence):
    last_char = sentence[-1]

    if last_char == '?':
        sentence_type = 'question'

    if last_char == '!':
        sentence_type = 'exclamation'
    else:
        sentence_type = 'normal'

    return 'Sentence is ' + sentence_type

print(get_type_of_sentence('Who?'))  # => 'Sentence is normal'
print(get_type_of_sentence('No'))    # => 'Sentence is normal'
print(get_type_of_sentence('No!'))   # => 'Sentence is exclamation'

We have added an exclamation checker for exclamation sentences. Technically this feature works, but it treats question sentences incorrectly. There are also problems with it in terms of semantics:

• The exclamation point is checked in any case, even if there is already a question mark
• The else branch is described for the second condition, but not for the first. Therefore the question sentence becomes normal'.

To remedy the situation, let's take another possibility of conditional construction:

def get_type_of_sentence(sentence):
    last_char = sentence[-1]

    if last_char == '?':
        sentence_type = 'question'
    elif last_char == '!':
        sentence_type = 'exclamation'
    else:
        sentence_type = 'normal'

    return 'Sentence is ' + sentence_type

print(get_type_of_sentence('Who?'))  # => 'Sentence is question'
print(get_type_of_sentence('No'))    # => 'Sentence is normal'
print(get_type_of_sentence('No!'))   # => 'Sentence is exclamation'

Now all the conditions are lined up in a single construction. The elif means "if the previous condition is not satisfied, but the current condition is satisfied". This is the scheme:

• If the last letter is ? then'question'`
• if the last letter is !, then 'exclamation'
• other options are normal'.

Only one of the code blocks that refers to the whole if construct will be executed.

Instructions

The electronic map of Westeros that Sam implemented shows Stark allies in green circles, enemies in red, and neutral families in gray.

Write a function who_is_this_house_to_starks() for Sam that takes the family name as input and returns one of three values: 'friend', 'enemy', 'neutral'.

Rules of Determination:

• Friends ('friend'): 'Karstark', 'Tully'
• Enemies ('enemy'): 'Lannister', 'Frey'
• Any other families are considered neutral'.

Examples of calls:

print(who_is_this_house_to_starks('Karstark'))  # => 'friend'
print(who_is_this_house_to_starks('Frey'))      # => 'enemy'
print(who_is_this_house_to_starks('Joar'))      # => 'neutral'
print(who_is_this_house_to_starks('Ivanov'))    # => 'neutral'

Definitions

• else + if = elif a way of setting several alternative conditions.