pub fn first_entry(&mut self) -> Option<Entry<'_, K, V>> {
        let self_ptr: *mut _ = self;
        let root_node = self.root.as_mut()?.borrow_mut();
        let entry = root_node.first_entry();
        Some(Entry {
            vacant_key: None,
            inner: entry,
            self_ptr,
        })
    }
/// Returns the first entry in the map for in-place manipulation..
///
/// The key of the entry is the minimum key in the map.
///
/// # Examples
///
/// ```
/// use bptree::BpTreeMap;
///
/// let mut map = BpTreeMap::new();
/// assert!(map.first_entry().is_none());
///
/// map.insert(1, "One");
/// map.insert(2, "Two");
/// map.first_entry().unwrap().and_modify(|val| *val = "Another");
///
/// assert_eq!(map.first_key_value(), Some((&1, &"Another")));
Returns the first entry in the map for in-place manipulation
The key of the entry is the minimum key in the map.
Returns the first entry in the map for in - place manipulation The key of the entry is the minimum key in the map .
pub fn first_entry(&mut self) -> Option<Entry<'_, K, V>> {
        let self_ptr: *mut _ = self;
        let root_node = self.root.as_mut()?.borrow_mut();
        let entry = root_node.first_entry();
        Some(Entry {
            vacant_key: None,
            inner: entry,
            self_ptr,
        })
    }
pub fn first_entry ( & mut self ) -> Option < Entry < ' _ , K , V > > { let self_ptr : * mut _ = self ; let root_node = self . root . as_mut ( ) ? . borrow_mut ( ) ; let entry = root_node . first_entry ( ) ; Some ( Entry { vacant_key : None , inner : entry , self_ptr , } ) }
Returns the first entry in the map for in-place manipulation..
Returns the first entry in the map for in - place manipulation ..
&mut self
&mut self
examples
```
use bptree::BpTreeMap.

let mut map = BpTreeMap::new();
assert!(map.first_entry().is_none()).

map.insert(1, "One");
map.insert(2, "Two");
map.first_entry().unwrap().and_modify(|val| *val = "Another").


` ` ` use bptree :: BpTreeMap . let mut map = BpTreeMap :: new () ; assert! ( map . first_entry () . is_none () ) . map . insert ( 1 " One " ) ; map . insert ( 2 " Two " ) ; map . first_entry () . unwrap () . and_modify ( |val| * val = " Another " ) .