code: def diff_fromDelta(self, text1, delta):
      
      diffs = []
      pointer = 0  # Cursor in text1
      tokens = delta.split("\t")
      for token in tokens:
        if token == "":
          # Blank tokens are ok (from a trailing \t).
          continue
        # Each token begins with a one character parameter which specifies the
        # operation of this token (delete, insert, equality).
        param = token[1:]
        if token[0] == "+":
          param = urllib.parse.unquote(param)
          diffs.append((self.DIFF_INSERT, param))
        elif token[0] == "-" or token[0] == "=":
          try:
            n = int(param)
          except ValueError:
            raise ValueError("Invalid number in diff_fromDelta: " + param)
          if n < 0:
            raise ValueError("Negative number in diff_fromDelta: " + param)
          text = text1[pointer : pointer + n]
          pointer += n
          if token[0] == "=":
            diffs.append((self.DIFF_EQUAL, text))
          else:
            diffs.append((self.DIFF_DELETE, text))
        else:
          # Anything else is an error.
          raise ValueError("Invalid diff operation in diff_fromDelta: " +
              token[0])
      if pointer != len(text1):
        raise ValueError(
            "Delta length (%d) does not equal source text length (%d)." %
           (pointer, len(text1)))
      return diffs
docs: Given the original text1, and an encoded string which describes the
      operations required to transform text1 into text2, compute the full diff.
  
      Args:
        text1: Source string for the diff.
        delta: Delta text.
  
      Returns:
        Array of diff tuples.
  
      Raises:
        ValueError: If invalid input.