'The velocity Vector of this Point in the ReferenceFrame.
Parameters
frame : ReferenceFrame
The frame in which the returned velocity vector will be defined in
Examples
>>> from sympy.physics.vector import Point, ReferenceFrame
>>> N = ReferenceFrame(\'N\')
>>> p1 = Point(\'p1\')
>>> p1.set_vel(N, 10 * N.x)
>>> p1.vel(N)
10*N.x'

def vel(self, frame):

    _check_frame(frame)
    if (not (frame in self._vel_dict)):
        raise ValueError(((('Velocity    of    point    ' + self.name) + '    has    not    been    defined    in    ReferenceFrame    ') + frame.name))
    return self._vel_dict[frame]
