<filename>package/Y.py
class Y:
    def __init__(self, v0):
        self.v0 = v0
        self.g = 9.81

    def value(self, t):
        return self.v0*t - 0.5*self.g*t**2

    def formula(self):
        return "v0*t - 0.5*g*t**2; v0=%g" % self.v0

<filename>package/Y.py
class Y:
    def __init__(self, v0):
        self.v0 = v0
        self.g = 9.81

    def value(self, t):
        return self.v0*t - 0.5*self.g*t**2

    def formula(self):
        return "v0*t - 0.5*g*t**2; v0=%g" % self.v0
