def detectFileFormat(filename):
    """
    return format name by examining the last suffix of file name
    """
    suffixFormatDict = {
                        'gb': 'GenBank', 
                        'fa': 'FASTA', 
                        'fasta': 'FASTA', 
                        'gff3': 'GFF3'}
    suffix = filename.split('.')[-1]
    return(suffixFormatDict[suffix])