Determine the resistance class of the gene by searching the sets of genes included in every resistance FASTA
        file
        :param genename: Header string returned from analyses
        :param resistance_dict: Dictionary of resistance class: header
        :return: resistance class of the gene

def resistance(genename, resistance_dict):
        """
        Determine the resistance class of the gene by searching the sets of genes included in every resistance FASTA
        file
        :param genename: Header string returned from analyses
        :param resistance_dict: Dictionary of resistance class: header
        :return: resistance class of the gene
        """
        # Initialise a list to store the resistance class(es) for the gene
        resistance_list = list()
        # Iterate through the dictionary of the resistance class: set of gene names
        for resistance_class, gene_set in resistance_dict.items():
            # If the gene is presence in the set
            if genename in gene_set:
                # Set the resistance class appropriately
                resistance_list.append(resistance_class)
        # Create a comma-separated string of the sorted genes
        resistance = ','.join(sorted(resistance_list))
        # Return the calculated resistance class
        return resistance