code: func (om *OrdMap) Delete(key interface{}) {
  	rkey := ty.AssertType(key, om.ktype)
  
  	// Avoid doing work if we don't need to.
  	if !om.exists(rkey) {
  		return
  	}
  
  	keysLen := om.keys.Len()
  	for i := 0; i < keysLen; i++ {
  		if key == om.keys.Index(i).Interface() {
  			// om.keys = append(om.keys[:i], om.keys[i+1:]...)
  			om.keys = reflect.AppendSlice(
  				om.keys.Slice(0, i), om.keys.Slice(i+1, keysLen))
  			break
  		}
  	}
  
  	// Setting a key to a zero reflect.Value deletes the key from the map.
  	om.m.SetMapIndex(rkey, reflect.Value{})
  }
docs: // Delete has a parametric type:
  //
  //	func (om *OrdMap<K, V>) Delete(key K)
  //
  // Delete removes `key` from the map `om`.
  //
  // N.B. Delete is O(n) in the number of keys.