You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: generics.rs
    path of file: ./repos/darling/core/src/ast
    
    the code of the file until where you have to start completion: //! Types for working with generics

use std::iter::Iterator;
use std::slice::Iter;

use crate::{FromGenericParam, FromGe
    
    fn as_const_param(&self) -> Option<&C> {
        if let GenericParam::Const(ref val) = *self {
            Some(val)
        } else {
            None
        }
    }