input: Write a python function to search for a value in a linked list.
  assert search_in_linkedlist(llist, 3) == True
  assert search_in_linkedlist(llist, 4) == False
  assert search_in_linkedlist(llist, 1) == True
output: class Node:
      def __init__(self, value):
          self.value = value
          self.next = None
  
  class LinkedList:
      def __init__(self):
          self.head = None
  
  def search_in_linkedlist(llist, value):
      current = llist.head
      while current is not None:
          if current.value == value:
              return True
          current = current.next
      return False