input: 
  def is_subsequence(str1: str, str2: str) -> bool:
      """
      Check if the first string (str1) is a subsequence of the second string (str2).
      A subsequence is a sequence that can be derived from another sequence by deleting 
      some or no elements without changing the order of the remaining elements.
  
      >>> is_subsequence("abc", "qaxbcy")
      True
      >>> is_subsequence("abc", "acb")
      False
      """
      i, j = 0, 0
  
      while i < len(str1) and j < len(str2):
          if str1[i] == str2[j]:
              i += 1
          j += 1
  
      return i == len(str1)
  
output:     i, j = 0, 0
  
      while i < len(str1) and j < len(str2):
          if str1[i] == str2[j]:
              i += 1
          j += 1
  
      return i == len(str1)