### 5.8 Rotate_Left

In standard Ada, the `Rotate_Left`

function is available only
for the predefined modular types in package `Interfaces`

. However, in
GNAT it is possible to define a Rotate_Left function for a user
defined modular type or any signed integer type as in this example:

function Shift_Left
(Value : My_Modular_Type;
Amount : Natural)
return My_Modular_Type;

The requirements are that the profile be exactly as in the example
above. The only modifications allowed are in the formal parameter
names, and in the type of `Value`

and the return type, which
must be the same, and must be either a signed integer type, or
a modular integer type with a binary modulus, and the size must
be 8. 16, 32 or 64 bits.