              return False
          elif (st.S(0) + 1) != st.B(0):
              # Must break at the token boundary
              return False
          # Don't allow spaces to be the first word of a sentence
          elif Lexeme.c_check_flag(st.B_(0).lex, IS_SPACE):
              return False
          else:
              return True
  
      @staticmethod
      cdef int transition(StateClass st, int label) nogil:
 
</s> remove         while self.buffer_length() == 0 or self.stack_depth() == 0:
 </s> add         while self.buffer_length() == 0 \
        or self.stack_depth() == 0 \
        or Lexeme.c_check_flag(self.S_(0).lex, IS_SPACE): </s> remove @pytest.mark.xfail
 </s> add  </s> remove     doc.from_array([HEAD], numpy.asarray([[1, 0, -1, -2, -1, -1, -5,
                                           4, 3, 2, 1, 0, 2, 1, -3, 1, 1, -3, -7]],
                                 dtype='int32').T)
 </s> add 
              return False
          elif (st.S(0) + 1) != st.B(0):
              # Must break at the token boundary
              return False



          else:
              return True
  
      @staticmethod
      cdef int transition(StateClass st, int label) nogil:
keep keep keep keep replace replace replace keep keep keep keep keep
 * Unwind limit to sentence boundary detection that prevents it from inserting boundaries on whitespace. Replace it with a check for whitespace in StateClass.fast_forward, so that whitespace is LeftArced when it's on the stack. This should prevent the previous problem of whitespace-only sentences. Should fix Issue #184, but may cause further problems. Needs testing. 
spacy/syntax/arc_eager.pyx