class Node:
    def __init__(self, data: int | float | dict | tuple | set):
        self.data = data
        self.next = None
        self.prev = None

class LinkedList:
    def __init__(self):
        self.head = None

    def append(self, data):
        """Add a node with the given data to the end of the list."""
        new_node = Node(data)
        if not self.head:
            self.head = new_node
            return
        curr = self.head
        while curr.next:
            curr = curr.next
        curr.next = new_node
        new_node.prev = curr

    def prepend(self, data):
        """Add a node with the given data to the beginning of the list."""
        new_node = Node(data)
        if self.head:
            self.head.prev = new_node
        new_node.next = self.head
        self.head = new_node

    def insert_at_position(self, position, data):
        """Insert a node with the given data at the specified position (0-based)."""
        if position <= 0 or not self.head:
            self.prepend(data)
            return
        new_node = Node(data)
        curr = self.head
        index = 0
        while curr.next and index < position - 1:
            curr = curr.next
            index += 1
        new_node.next = curr.next
        new_node.prev = curr
        if curr.next:
            curr.next.prev = new_node
        curr.next = new_node

    def delete_value(self, value):
        """Remove the first node that contains the specified value."""
        curr = self.head
        while curr:
            if curr.data == value:
                if curr.prev:
                    curr.prev.next = curr.next
                else:
                    self.head = curr.next
                if curr.next:
                    curr.next.prev = curr.prev
                return True
            curr = curr.next
        return False

    def search(self, value):
        """Return True if a node with the specified value exists, otherwise False."""
        curr = self.head
        while curr:
            if curr.data == value:
                return True
            curr = curr.next
        return False

    def print_list(self):
        """Print all elements in the list in order."""
        elems = []
        curr = self.head
        while curr:
            elems.append(str(curr.data))
            curr = curr.next
        print(" <-> ".join(elems))
        

def build_dbl_linked_list_range(start, end, step):
    dll = LinkedList()
    for elem in range(start, end, step):
        dll.append(elem)
    dll.print_list()       
    return

    


# Example usage
if __name__ == "__main__":
    dll = LinkedList()
    dll.append(10)
    dll.append(20)
    dll.prepend(5)
    dll.insert_at_position(1, 7)
    dll.print_list()              # 5 <-> 7 <-> 10 <-> 20
    print(dll.search(10))         # True
    print(dll.search(100))        # False
    dll.delete_value(7)
    dll.print_list()              # 5 <-> 10 <-> 20
    dll.delete_value(5)
    dll.print_list()              # 10 <-> 20
    dll.insert_at_position(1, 15)
    dll.print_list()              # 10 <-> 15 <-> 20
    print(dll.search(15))         # True 
    dll.append({'apple': 4})
    dll.append({'beet': 7})
    dll.append({'corn': 5})
    dll.append({'grape': 9})
    dll.append((4, 9))
    dll.append(('hello', 'world'))
    dll.append({5, 8, 1, 8, 10})        # Only unique values appear in the appended set  -> {8, 1, 10, 5}
    dll.print_list()
    
    build_dbl_linked_list_range(2, 21, 2)