Whoever, in driving, leading or propelling a vehicle along a street, fails, except in the case of actual necessity —
(a) to keep to the left, and
(b) When he is passing a vehicle going in the same direction, to keep to the right of that vehicle, shall be liable on conviction to a fine which may extend to ten rupees.
Exception— This section shall not apply in the case of a municipality wholly or in part situated in a hilly tract.