code: def grep(self, needle):
          
          result = []
          for line in self.contents:
              if needle in line:
                  result.append(line)
          if result:
              return result
          return False
docs: Search all lines in file for substring 'needle'.
              equiv to: `grep "needle" ./file`
  
          Return matching lines as a List of Strings.
          If no matches returns False
  
          :param needle: String; word or phrase to search for.
          :return: List of Strings, or False.