input: from typing import List
  
  def is_subsequence(subseq: str, seq: str) -> bool:
      """Check if the given substring is a subsequence of the given string.
      >>> is_subsequence('abc', 'qaxbcy')
      True
      >>> is_subsequence('abc', 'acb')
      False
      """
output:     i, j = 0, 0
      while i < len(subseq) and j < len(seq):
          if subseq[i] == seq[j]:
              i += 1
          j += 1
      return i == len(subseq)