title: How to copy linked list in Python?
body: <p>class _ListNode:</p>
  
  <pre><code>class _ListNode:
      def __init__(self, value, next_):
          """
          -------------------------------------------------------
          Initializes a list node.
          Use: node = _ListNode(value, _next)
          -------------------------------------------------------
          Preconditions:
              _value - data value for node (?)
              _next - another list node (_ListNode)
          Postconditions:
              Initializes a list node that contains a copy of value
              and a link to the next node in the list.
          -------------------------------------------------------
          """
          self._value = copy.deepcopy(value)
          self._next = next_
          return
  </code></pre>
  
  <p>class List: </p>
  
  <pre><code>class List:
      def __init__(self):
          """
          -------------------------------------------------------
          Initializes an empty list.
          Use: l = List()
          -------------------------------------------------------
          Postconditions:
              Initializes an empty list.
          -------------------------------------------------------
          """
          self._front = None
          self._count = 0
          return
      def copy(self):
          """
          -------------------------------------------------------
          Duplicates the current list to a new list in the same order.
          Use: new_list = l.copy()
          -------------------------------------------------------
          Postconditions:
              returns:
              new_list - a copy of self (List)
          -------------------------------------------------------
  
          """
  </code></pre>
  
  <p>The requirement is to write the copy function.</p>
  
  <p>But when I finish this function as my opinion the new list only contains one item or None item.</p>
  
  <p>Does anyone could tell me how to finish this function?</p>