code: public boolean _attributeStreamIsAllocated(int semantics) {
  		throwIfEmpty();
  
  		int attributeIndex = m_description.getAttributeIndex(semantics);
  
  		if (attributeIndex >= 0 && m_vertexAttributes[attributeIndex] != null)
  			return true;
  
  		return false;
  	}
docs: Checked vs. Jan 11, 2011