def arbitrary_point(self, parameter='t'):
        t = _symbol(parameter)
        if t.name in (f.name for f in self.free_symbols):
            raise ValueError('Symbol %s already appears in object '
            'and cannot be used as a parameter.' % t.name)
        # multiply on the right so the variable gets
        # combined witht he coordinates of the point
        return self.p1 + (self.p2 - self.p1)*t
A parameterized point on the Line.
dataset/ETHPy150Open sympy/sympy/sympy/geometry/line.py/LinearEntity.arbitrary_point