def check(self):
        if isinstance(self.n, Guard):
            return False
        if self.digram() not in digrams:
            digrams[self.digram()] = self
            return False
        found = digrams[self.digram()]
        if found.n != self:
            self.match(self, found)
        return True
Checks a new digram to figure out what to do with it.
dataset/ETHPy150Open ResilientScience/wot/wot/sequitur.py/Symbol.check