new_contents: class Solution:
      def strStr(self, haystack, needle):
          """
          :type haystack: str
          :type needle: str
          :rtype: int
          """
          if len(needle)==0:
              return 0
          for i in range(len(haystack)-len(needle)+1):
              if haystack[i:i+len(needle)] == needle:
                  return i
          return -1
              
                  
                  
  
  
subject: Implement strStr()