const DNATranscriber = {
    G: 'C',
    C: 'G',
    T: 'A',
    A: 'U'
};

export default class Transcriptor {
    toRna(dna: string) {
        const codons = [...dna];
        if (!isValidSequence(codons)) {
            throw Error('invalid sequence');
        }
        const transcribedRNA = codons.map(codon => DNATranscriber[codon]);
        return transcribedRNA;
    }
}

function isValidSequence(values: string[]): values is Array {
    return values.every(isValidCodon);
}
function isValidCodon(value: string): value is keyof typeof DNATranscriber {
    return value in DNATranscriber;
}