from typing import Counter


def a_scramble(str_1,str_2):
    """Test if all the letters of word a are contained in word b"""
    str_1 = str_1.upper()
    str_2 = str_2.upper()
    letters = Counter(str_1)
    letters.subtract(Counter(str_2))
    return all(v >= 0 for v in letters.values())