How to define a =copy hook for a distinct cstring type?

[Isofruit]

Is `strlen` the proc `c_strlen` in `std/segfaults`? If so, how do you use it?

I tried this
    
    
    import std/segfaults
    let a: cstring = "lalala"
    echo a.c_strlen()
    
    
    Run

as well as just
    
    
    let a: cstring = "lalala"
    echo a.strlen
    
    
    Run

In case it's a proc somewhere in std/systems that I just fail to find. Neither 
can compile because they can't find strlen or c_strlen.