def amino_acid_chunks(threecharseq):
    """
    Expects a three character string as a parameter and returns
    the corresponding single character AminoAcid

    :param threecharseq: a sequence of three characters
    :return: A string representing the animo acid chunk for that sequence
    """

    ###################################################################
    #  This function was already completed correctly! No changes needed!
    ###################################################################

    # We haven't learned about dictionaries yet, but here is one for the extra curious.
    # You aren't expected to know what this is yet.
    translator = {"GCA": "A", "GCC": "A", "GCG": "A", "GCU": "A",
                  "AGA": "R", "AGG": "R", "CGA": "R", "CGC": "R", "CGG": "R", "CGU": "R",
                  "GAC": "D", "GAU": "D",
                  "AAC": "N", "AAU": "N",
                  "UGC": "C", "UGU": "C",
                  "GAA": "E", "GAG": "E",
                  "CAA": "Q", "CAG": "Q",
                  "GGA": "G", "GGC": "G", "GGU": "G", "GGG": "G",
                  "CAC": "H", "CAU": "H",
                  "AUA": "I", "AUC": "I", "AUU": "I",
                  "UUA": "L", "UUG": "L", "CUA": "L", "CUC": "L", "CUG": "L", "CUU": "L",
                  "AAA": "K", "AAG": "K",
                  "AUG": "M",
                  "UUC": "F", "UUU": "F",
                  "CCA": "P", "CCC": "P", "CCG": "P", "CCU": "P",
                  "AGC": "S", "AGU": "S", "UCA": "S", "UCC": "S", "UCG": "S", "UCU": "S",
                  "ACA": "T", "ACC": "T", "ACG": "T", "ACU": "T",
                  "UGG": "W",
                  "UAC": "Y", "UAU": "Y",
                  "GUA": "V", "GUC": "V", "GUG": "V", "GUU": "V",
                  "UAA": "*", "UAG": "*", "UGA": "*"}

    if threecharseq in translator.keys():
        return translator[threecharseq]     # Given any 3 letter sequence, this returns the amino acid for that sequence
    else:
        return "?"                          # Returns a question mark if the input is invalid