from typing import List
from typing import Counter


def count_words(sentences: List[str]) -> Counter:

    """

    A function that computes word frequencies in a list of sentences.

    Args:
        sentences: list of sentences

    Returns:
        Counter {"word": frequency}

    Example:
    >>> count_words(["this is a house"])
    Counter({'this': 1, 'is': 1, 'a': 1, 'house': 1})
    >>> count_words(["this is a house", "this is a house"])
    Counter({'this': 2, 'is': 2, 'a': 2, 'house': 2})
    >>> count_words([])
    Counter()
    """

    words: List[str] = []

    for sentence in sentences:
        words.extend(sentence.split())

    words_counter = Counter(words)

    return words_counter