def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
def drawMe(self, g):
        self.g = g
        r = 5
        # 繪出三個頂點
        self.p1.drawMe(self.g,r)
        self.p2.drawMe(self.g,r)
        self.p3.drawMe(self.g,r)
        line1 = Line(self.p1,self.p2)
        line2 = Line(self.p1,self.p3)
        line3 = Line(self.p2,self.p3)
        # 繪出三邊線
        line1.drawMe(self.g)
        line2.drawMe(self.g)
        line3.drawMe(self.g)