from unittest import defaultTestLoader


def to_rna(dna_strand):
    transcribed_rna_strand: str = ""
    for nucleotide in dna_strand:
        match nucleotide:
            case "G":
                transcribed_rna_strand += "C"
            case "C":
                transcribed_rna_strand += "G"
            case "T":
                transcribed_rna_strand += "A"
            case "A":
                transcribed_rna_strand += "U"
            case _:
                transcribed_rna_strand += nucleotide
    return transcribed_rna_strand