  
      @property
      def is_full(self):
          """RETURNS (bool): `True` if no slots are available for new keys."""
          return len(self._unset) == 0
  
      @property
      def n_keys(self):
          """RETURNS (int) The number of keys in the table. Note that this is the
          number of all keys, not just unique vectors."""
 
</s> remove         if i in self._unset:
            self._unset.remove(i)
 </s> add         if self._unset.count(i):
            self._unset.erase(self._unset.find(i)) </s> remove             if row in self._unset:
                self._unset.remove(row)
 </s> add             if self._unset.count(row):
                self._unset.erase(self._unset.find(row)) </s> remove             self._unset = set()
 </s> add             self._unset = cppset[int]() </s> remove             if row not in self._unset:
 </s> add             if not self._unset.count(row): </s> remove     cdef public object _unset
 </s> add     cdef cppset[int] _unset
        return self._unset.size() == 0
  
      @property
      def is_full(self):
          """RETURNS (bool): `True` if no slots are available for new keys."""
        return self._unset.size() == 0
  
      @property
      def n_keys(self):
          """RETURNS (int) The number of keys in the table. Note that this is the
          number of all keys, not just unique vectors."""
keep keep keep keep replace keep keep keep keep keep
 [2032] - Changed python set to cpp stl set (#2170)

Changed python set to cpp stl set #2032 

## Description

Changed python set to cpp stl set. CPP stl set works better due to the logarithmic run time of its methods. Finding minimum in the cpp set is done in constant time as opposed to the worst case linear runtime of python set. Operations such as find,count,insert,delete are also done in either constant and logarithmic time thus making cpp set a better option to manage vectors.
Reference : http://www.cplusplus.com/reference/set/set/

### Types of change
Enhancement for `Vectors` for faster initialising of word vectors(fasttext) 
spacy/vectors.pyx