code: def lastAnchor(self, block, column):
          
          currentPos = -1
          currentBlock = None
          currentColumn = None
          currentChar = None
          for char in '({[':
              try:
                  foundBlock, foundColumn = self.findBracketBackward(block, column, char)
              except ValueError:
                  continue
              else:
                  pos = foundBlock.position() + foundColumn
                  if pos > currentPos:
                      currentBlock = foundBlock
                      currentColumn = foundColumn
                      currentChar = char
                      currentPos = pos
  
          return currentBlock, currentColumn, currentChar
docs: Find the last open bracket before the current line.
          Return (block, column, char) or (None, None, None)