def clean_input_reads(records):
    """Add a cleaned_seq attribute to records that do not have one

    Use this to convert a stream of records that might not have a
    `cleaned_seq` attribute to one that does. Use this to extend
    Records loaded by `screed.open()`. It is a mistake to apply
    this to a `ReadParser` stream.
    """
    for record in records:
        record.cleaned_seq = record.sequence.upper().replace('N', 'A')
        yield record
