def step4(self):
        """step4() takes off -ant, -ence etc., in context <c>vcvc<v>."""
        if self.b[self.k - 1] == 'a':
            if self.ends("al"):
                pass
            else:
                return
        elif self.b[self.k - 1] == 'c':
            if self.ends("ance"):
                pass
            elif self.ends("ence"):
                pass
            else:
                return
        elif self.b[self.k - 1] == 'e':
            if self.ends("er"):
                pass
            else:
                return
        elif self.b[self.k - 1] == 'i':
            if self.ends("ic"):
                pass
            else:
                return
        elif self.b[self.k - 1] == 'l':
            if self.ends("able"):
                pass
            elif self.ends("ible"):
                pass
            else:
                return
        elif self.b[self.k - 1] == 'n':
            if self.ends("ant"):
                pass
            elif self.ends("ement"):
                pass
            elif self.ends("ment"):
                pass
            elif self.ends("ent"):
                pass
            else:
                return
        elif self.b[self.k - 1] == 'o':
            if self.ends("ion") and (self.b[self.j] ==
               's' or self.b[self.j] == 't'):
                pass
            elif self.ends("ou"):
                pass
            # takes care of -ous
            else:
                return
        elif self.b[self.k - 1] == 's':
            if self.ends("ism"):
                pass
            else:
                return
        elif self.b[self.k - 1] == 't':
            if self.ends("ate"):
                pass
            elif self.ends("iti"):
                pass
            else:
                return
        elif self.b[self.k - 1] == 'u':
            if self.ends("ous"):
                pass
            else:
                return
        elif self.b[self.k - 1] == 'v':
            if self.ends("ive"):
                pass
            else:
                return
        elif self.b[self.k - 1] == 'z':
            if self.ends("ize"):
                pass
            else:
                return
        else:
            return
        if self.m() > 1:
            self.k = self.j
dataset/ETHPy150Open CGATOxford/cgat/scripts/revigo.py/PorterStemmer.step4/original