def enc_consume(carrier, nsyms):
  chrs = defaultdict(int)

  i = 0  # see this?

  for i,c in enumerate(carrier):
    # `i` is not used in the loop
    chrs[c] += 1
    if len(chrs) == nsyms:
      break

  return chrs, carrier[i+1:]  # but it's used here

def enc_consume(carrier, nsyms):
    characters = defaultdict(int)
    stream = iter(carrier)

    for char in stream:
        characters[char] += 1
        if len(characters) >= nsyms:
             break

    return characters, ''.join(stream)

def enc_consume(carrier, nsyms):
    first_unused_idx = 0
    char_cnt = defaultdict(int)
    while first_unused_idx < len(carrier) and len(char_cnt) < nsyms:
        char_cnt[carrier[first_unused_idx]] += 1
        first_unused_idx += 1
    return char_cnt, carrier[first_unused_idx:]