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: trampoline.rs
    path of file: ./repos/artichoke/artichoke-backend/src/extn/stdlib/securerandom
    
    the code of the file until where you have to start completion: //! Glue between mruby FFI and `securerandom` Rust implementation.

use crate::convert::im
    
pub fn alphanumeric(interp: &mut Artichoke, len: Option<Value>) -> Result<Value, Error> {
    let alpha = if let Some(len) = len {
        let len = implicitly_convert_to_int(interp, len)?;
        securerandom::alphanumeric(Some(len))?
    } else {
        securerandom::alphanumeric(None)?
    };
    let alpha = spinoso_string::String::ascii(alpha);
    spinoso_string::String::alloc_value(alpha, interp)
}