'Return a tree node representing an error.  This node records the
tokens consumed during error recovery.  The start token indicates the
input symbol at which the error was detected.  The stop token indicates
the last symbol consumed during recovery.
You must specify the input stream so that the erroneous text can
be packaged up in the error node.  The exception could be useful
to some applications; default implementation stores ptr to it in
the CommonErrorNode.
This only makes sense during token parsing, not tree parsing.
Tree parsing should happen only when parsing and tree construction
succeed.'

def errorNode(self, input, start, stop, exc):

    raise NotImplementedError
