Uses .tfa files included in the ResFinder database to determine the resistance class of gene matches
        :param targetpath: Path to database files
        :return: Dictionary of resistance class: gene set

def classes(targetpath):
        """
        Uses .tfa files included in the ResFinder database to determine the resistance class of gene matches
        :param targetpath: Path to database files
        :return: Dictionary of resistance class: gene set
        """
        # Initialise dictionary to store results
        resistance_dict = dict()
        # Find all the .tfa files in the folder
        resistance_files = sorted(glob(os.path.join(targetpath, '*.tfa')))
        # Iterate through each file
        for fasta in resistance_files:
            # Extract the resistance class from the file name and path
            resistance_class = os.path.splitext(os.path.basename(fasta))[0]
            # Initialise the resistance class as a set in the dictionary
            resistance_dict[resistance_class] = set()
            # Open the file
            with open(fasta) as resistance:
                # Iterate through the FASTA records
                for record in SeqIO.parse(resistance, 'fasta'):
                    # Replace dashes with underscores
                    record.id = record.id.replace('-', '_')
                    # Add the gene name to the set
                    resistance_dict[resistance_class].add(record.id)
        return resistance_dict