Counts characters of a specified group size that appear in a sequence

character_count.py

from collections import defaultdict

dna: str = "AAACGATGCTAGCATCGGGGCTAGCTACGATTCATCAGCATACGT"

def character_count(count: int, seq: str, order: bool = True) -> dict[str, int]|str:

  seqlen = len(seq)
  
  charactermatches: dict[str, int] = defaultdict(int)
  
  if count > seqlen:
    return "Count is greater than sequence length! Cannot compute count."

  if count == seqlen:
    charactermatches[seq] += 1
    charactermatches = dict(charactermatches)
    return charactermatches

  for start, _ in enumerate(seq):
    end = start+count
    if end > len(seq):
      break
      
    key: str = seq[start:end]

    #combines matches that contain 
    #the same letters in different order
    if not order: 
      key = "".join(sorted(key))
      
    charactermatches[key] += 1
    
  charactermatches = dict(charactermatches)
  
  return charactermatches

print(character_count(2,dna))