text: #coding=utf8
  
  class Error(Exception):
      """Base class for utils in this module."""
      pass
  
  class LengthError(Error):
      """Exception raised for length-problem in the input.
      """
      pass
  
  class InputTypeError(Error):
      """Exception raised for type-problem in the input.
      """
      pass
  class SizeTypeError(Error):
      """Exception raised for sizeType-problem in the input.
      """
      pass
  
  class ListValueTypeError(Error):
      """Exception raised for errors in the input.
      Attributes:
          message -- explanation of the error
      """
  
      def __init__(self, message):
          self.message = message
  
  class TransitionError(Error):
      """Raised when the user  size seems not normal.
      Attributes:
          message -- explanation of why the exception occured
      """
  
      def __init__(self,message):
          self.message = message