human
Complete the below
def FastaIterator(handle, alphabet=single_letter_alphabet, title2ids=None):

    ''''Generator function to iterate over Fasta records (as SeqRecord objects).
    Arguments:
    - handle - input file
    - alphabet - optional alphabet
    - title2ids - A function that, when given the title of the FASTA
    file (without the beginning >), will return the id, name and
    description (in that order) for the record as a tuple of strings.
    If this is not given, then the entire title line will be used
    as the description, and the first word as the id and name.
    By default this will act like calling Bio.SeqIO.parse(handle, "fasta")
    with no custom handling of the title lines:
    >>> with open("Fasta/dups.fasta") as handle:
    ...     for record in FastaIterator(handle):
    ...         print(record.id)
    alpha
    beta
    gamma
    alpha
    delta
    However, you can supply a title2ids function to alter this:
    >>> def take_upper(title):
    ...     return title.split(None, 1)[0].upper(), "", title
    >>> with open("Fasta/dups.fasta") as handle:
    ...     for record in FastaIterator(handle, title2ids=take_upper):
    ...         print(record.id)
    ALPHA
    BETA
    GAMMA
    ALPHA
    DELTA'
    '''
assistant
#Here is the Python code you requested.
    if title2ids:
        for (title, sequence) in SimpleFastaParser(handle):
            (id, name, descr) = title2ids(title)
            (yield SeqRecord(Seq(sequence, alphabet), id=id, name=name, description=descr))
    else:
        for (title, sequence) in SimpleFastaParser(handle):
            try:
                first_word = title.split(None, 1)[0]
            except IndexError:
                assert (not title), repr(title)
                first_word = ''
            (yield SeqRecord(Seq(sequence, alphabet), id=first_word, name=first_word, description=title))