input: Write a function that determines if the first string is a subsequence of the second string. If it is, return True, otherwise return False. If either string is empty, return True.
  def is_subsequence(str1, str2):
      i = 0
      j = 0
      
      while(i < len(str1) and j < len(str2)):
          if str1[i] == str2[j]:
              i += 1
          j += 1
          
      return i == len(str1)
      
  assert is_subsequence("abc", "qaxbcy")==True
  assert is_subsequence("abc", "dfe")==False
  assert is_subsequence("hello", "hellomydearfriend")==True
  assert is_subsequence("xyz", "abcde")==False
  assert is_subsequence("", "any")==True
  assert is_subsequence("any", "")==True
  assert is_subsequence("", "")==True
output: def is_subsequence(str1, str2):
      if not str1 or not str2:
          return True
      
      i = 0
      j = 0
      
      while i < len(str1) and j < len(str2):
          if str1[i] == str2[j]:
              i += 1
          j += 1
          
      return i == len(str1)