def chars_in_dict(seqdict):
    """Return ordered list of characters in dictionary of sequences."""
    # Initialize set of characters
    characters = set([])
    # Iterate over sequences
    for seqid in seqdict.keys():
        # Update the set of characters with those in the current sequence
        characters.update(set(list(seqdict[seqid])))
    # Return characters as an ordered list
    return sorted(list(characters))