pub fn remove(self) -> MetadataValue<VE> {
        let value = self.inner.remove();
        MetadataValue::unchecked_from_header_value(value)
    }
Remove the entry from the map.

All values associated with the entry are removed and the first one is
returned. See `remove_entry_mult` for an API that returns all values.

# Examples

```
# use tonic::metadata::*;
let mut map = MetadataMap::new();
map.insert("host", "world".parse().unwrap());

if let Entry::Occupied(e) = map.entry("host").unwrap() {
let mut prev = e.remove();
assert_eq!("world", prev);
}

assert!(!map.contains_key("host"));
```
tonic/src/metadata/map.rs