Example:
def dna_token(dna_string, kmer, step)
dna = "ACTGTCGTACAGTGACCAGTGGTAGT"
kmerized_dna = dna_token(dna, 5, 1)
ACTGTCGTACAGTGACCAGTGGTAGT
ACTGT CTGTC TGTCG GTCGT TCGTA CGTAC GTACA TACAG ACAGT CAGTG AGTGA GTGAC TGACC GACCA ACCAG CCAGT CAGTG AGTGG GTGGT TGGTA GGTAG GTAGT