code: def isPositionValid(self, line: int, column: int):
          
          if (line < 0) or (column < 0):
              return False
  
          last_line, last_col = self.getNumLinesAndColumns()
          if line > last_line:
              return False
  
          if column <= len(self.text(line)):
              return True
          else:
              return False
docs: Return **True** if ``line`` and ``column`` denote a valid
          position.
  
          |Args|
  
          * ``line`` (**int**): line number
          * ``column`` (**int**): column in line ``line``
  
          |Returns|
  
          **bool**: **True** if ``line`` and ``column`` specify a
            valid point in the document, **False** otherwise.
  
          |Raises|
  
          * **None**