lojix/logic/src/main/com/thesett/aima/logic/fol/isoprologparser/TokenSource.java
public Token poll()
    {
        if (token.next == null)
        {
            token.next = tokenManager.getNextToken();
        }

        token = token.next;

        return token;
    }
public Token poll()
    {
        if (token.next == null)
        {
            token.next = tokenManager.getNextToken();
        }

        token = token.next;

        return token;
    }
Retrieves and removes the head token, or <tt>null</tt> if there are no more tokens.

@return The head token, or <tt>null</tt> if there are no more tokens.