code: @Override
      public boolean containsKey(Object key) {
  	int hash = hash(key);
  	return segmentFor(hash).containsKey(key, hash);
      }
docs: Tests if the specified object is a key in this table.
  
  @param key possible key
  @return <tt>true</tt> if and only if the specified object is a key in this table, as determined
  by the <tt>equals</tt> method; <tt>false</tt> otherwise.
  @throws NullPointerException if the specified key is null