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: core.rs
    path of file: ./repos/indexmap/src/map
    
    the code of the file until where you have to start completion: //! This is the core implementation that doesn't depend on the hasher at all.
//!
//! The methods of `IndexMapCore` don't use any Hash properties of K.
//!
//! It's cleaner to separate them out, then the comp
    
    pub(crate) fn pop(&mut self) -> Option<(K, V)> {
        if let Some(entry) = self.entries.pop() {
            let last = self.entries.len();
            erase_index(&mut self.indices, entry.hash, last);
            Some((entry.key, entry.value))
        } else {
            None
        }
    }