'Checks if the vocabulary is compiled by checking if the revision,
languagemodel and dictionary files are readable.
Returns:
True if this vocabulary has been compiled, else False'

@property
def is_compiled(self):

    return (super(self.__class__, self).is_compiled and os.access(self.languagemodel_file, os.R_OK) and os.access(self.dictionary_file, os.R_OK))
