A string representing the key of the tree node.
Optionalvalue: VThe value parameter is an optional parameter of type V. It represents the
value associated with the node. If no value is provided, it defaults to undefined.
Optionalchildren: TreeNode<V>[]The children parameter is an optional array of TreeNode<V>
objects. It represents the child nodes of the current node. If no children are provided, the
default value is an empty array.
The function returns an array of TreeNode objects or undefined.
The children property is being returned. It is of type TreeNode<V>[] | undefined,
which means it can either be an array of TreeNode<V> objects or undefined.
The function sets the value of the children property of a TreeNode object.
The function returns the value of the protected variable _key.
The value of the _key property, which is a string.
The above function sets the value of a protected variable called "key".
The value parameter is a string that represents the value to be assigned to the key.
The function returns the value stored in a variable, or undefined if the variable is empty.
The value of the variable _value is being returned.
The function sets the value of a variable.
The parameter "value" is of type "V | undefined", which means it can accept a value of type "V" or it can be undefined.
The constructor function initializes a TreeNode object with a key, optional value, and optional children.