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: warn.rs
    path of file: ./repos/ferrocarril/mruby/src
    
    the code of the file until where you have to start completion: use log::warn;

use crate::convert::FromMrb;
use crate::sys;
use crate::value::{Value, ValueLike};
use crate::{Mrb, MrbError};

/// Interpreters that implement [`MrbWarn`] expose methods for emitting warnings
/// during execution.
///
/// Some functionality required to be compliant with ruby-spec is deprecated or
/// invalid behavior and ruby-spec exp
    
    fn warn(&self, message: &str) -> Result<(), MrbError> {
        warn!("rb warning: {}", message);
        let mrb = self.borrow().mrb;
        let kernel = unsafe {
            let stderr = sys::mrb_gv_get(mrb, self.borrow_mut().sym_intern("$stderr"));
            if sys::mrb_sys_value_is_nil(stderr) {
                return Ok(());
            }
            let kernel = (*mrb).kernel_module;
            Value::new(self, sys::mrb_sys_module_value(kernel))
        };
        kernel.funcall::<(), _, _>("warn", &[Value::from_mrb(self, message)])
    }