  
      @staticmethod
      cdef int transition(StateClass st, int label) nogil:
          st.set_break(st.B(0))
          while st.stack_depth() >= 2 and st.has_head(st.S(0)):
              st.pop()
          if st.stack_depth() == 1:
              st.pop()
          else:
              st.unshift()
  
      @staticmethod
      cdef int cost(StateClass s, const GoldParseC* gold, int label) nogil:
          return Break.move_cost(s, gold) + Break.label_cost(s, gold, label)
  
 
</s> remove         # When we break, we can't reach any arcs between stack and buffer
        # So cost is number of deps between S0...Sn and B0...Nn
        cdef int cost = 0
        cdef int i, j, B_i, S_i
        for i in range(s.buffer_length()):
            B_i = s.B(i)
            for j in range(s.stack_depth()):
                S_i = s.S(j)
                cost += gold.heads[B_i] == S_i
                cost += gold.heads[S_i] == B_i
        return cost
 </s> add         # Check for sentence boundary --- if it's here, we can't have any deps
        # between stack and buffer, so rest of action is irrelevant.
        s0_root = _get_root(s.S(0), gold)
        b0_root = _get_root(s.B(0), gold)
        if s0_root == -1 or b0_root == -1 or s0_root != b0_root:
            return 0
        else:
            return 1 </s> remove             elif self.buffer_length() >= 2 and self.stack_depth() == 0:
 </s> add             elif (self.length - self._b_i) >= 1 and self.stack_depth() == 0:
        st.fast_forward()
  
      @staticmethod
      cdef int transition(StateClass st, int label) nogil:
          st.set_break(st.B(0))
        st.fast_forward()
        st.fast_forward()
        st.fast_forward()
        st.fast_forward()
        st.fast_forward()
        st.fast_forward()
  
      @staticmethod
      cdef int cost(StateClass s, const GoldParseC* gold, int label) nogil:
          return Break.move_cost(s, gold) + Break.label_cost(s, gold, label)
  
keep keep keep keep replace replace replace replace replace replace keep keep keep keep keep
 * Fixes to unshift/fast-forward strategy. Getting 91.55 greedy on NW dev, gold preproc 
spacy/syntax/arc_eager.pyx