Can someone explain why this is not an error?

[canalpay]

I think :

Ýmmutable, type automatic moments. Because, it is StorageClass.

Example :
import std.stdio;
void main()
{
    immutable a = 3, b = 4.2, c = true;
    writeln(typeof(a).stringof,typeof(b).stringof,typeof(c).stringof);
}

or 

import std.stdio;
void main()
{
    auto a = 3, b = 4.2, c = true;
    writeln(typeof(a).stringof,typeof(b).stringof,typeof(c).stringof);
}

Keywords(StorageClass):
        abstract
        auto
        const
        deprecated
        extern
        final
        immutable
        shared
        nothrow
        override
        pure
        scope
        static
        synchronized

I don't know English. I'm sorry if misspelled.