from typing import Counter


def lower_ngrams(ngrams: Counter) -> Counter:
    """
    Lowercase all strings in the Counter.

    Parameters
    ----------
    ngrams : Counter
        A Counter of strings, in this case n-grams

    Returns
    -------
    Counter
        A Counter of lowercased strings
    """
    lowercased_ngrams = Counter()
    # Sadly, this doesn't work with a dictionary comprehension
    for k, v in ngrams.items():
        lowercased_ngrams.update({k.lower(): v})
    return lowercased_ngrams