parameters: (self, pattern)
docstring: Class constructor.
  
          The only mandatory argument should be the pattern string.
  
          This method B{MUST} be reimplemented by subclasses of L{Pattern}.
docstring_summary: Class constructor.
docstring_tokens: Class constructor .
function: def __init__(self, pattern):
          """
          Class constructor.
  
          The only mandatory argument should be the pattern string.
  
          This method B{MUST} be reimplemented by subclasses of L{Pattern}.
          """
          raise NotImplementedError()
function_tokens: def __init__ ( self , pattern ) : raise NotImplementedError ( )