pub fn and_modify(mut self, f: impl FnOnce(&mut T)) -> Self {
        if let Entry::Occupied(occupied) = &mut self {
            f(occupied.get_mut().deref_mut());
        }
        self
    }
/// Provides in-place mutable access to an occupied entry before any potential inserts.
Provides in-place mutable access to an occupied entry before any potential inserts.
Provides in - place mutable access to an occupied entry before any potential inserts .
pub fn and_modify(mut self, f: impl FnOnce(&mut T)) -> Self {
        if let Entry::Occupied(occupied) = &mut self {
            f(occupied.get_mut().deref_mut());
        }
        self
    }
pub fn and_modify ( mut self , f : impl FnOnce ( & mut T ) ) -> Self { if let Entry :: Occupied ( occupied ) = & mut self { f ( occupied . get_mut ( ) . deref_mut ( ) ) ; } self }
Provides in-place mutable access to an occupied entry before any potential inserts.
Provides in - place mutable access to an occupied entry before any potential inserts .
mut self
f
impl FnOnce(&mut T)
mut self
f
impl FnOnce(&mut T)