  Canonical formalism for SO(2) is developed. This group can be seen as a toy
model of the Hamilton-Dirac mechanics with constraints. The Lagrangian and
Hamiltonian are explicitly constructed and their physical interpretation are
given. The Euler-Lagrange and Hamiltonian canonical equations coincide with the
Lie equations. It is shown that the constraints satisfy CCR. Consistency of the
constraints is checked.
