How to find documentation of hard-to-google keywords and symbols

[dnspies]

On Thursday, 3 April 2014 at 16:10:45 UTC, bearophile wrote:
> dnspies:
>
>> I still don't know where to find documentation for "is" (which 
>> I just found out in another forum post is overloaded for 
>> dynamic arrays).  Can users overload the meaning of "is" 
>> themselves?
>
> Here you find info on the D language:
> http://dlang.org/spec.html
>
> "is" is an operator, so it's an expression, so you find it here:
> http://dlang.org/expression
>
> Bye,
> bearophile

I don't see where it talks about how to compare dynamic arrays 
with "is".  It says:

The forms of the IsExpression are:

1.    is ( Type )
...
2.    is ( Type : TypeSpecialization )
...
3.    is ( Type == TypeSpecialization )
...
4.    is ( Type Identifier )
...
5.    is ( Type Identifier : TypeSpecialization )
...
6.    is ( Type Identifier == TypeSpecialization )
...
7.    is ( Type : TypeSpecialization , TemplateParameterList )
is ( Type == TypeSpecialization , TemplateParameterList )
is ( Type Identifier : TypeSpecialization , TemplateParameterList 
)
is ( Type Identifier == TypeSpecialization , 
TemplateParameterList )
...

This doesn't explain "a is b" where a and b are both dynamic 
arrays.