Each time the method is called a "not" is added to the front of the text representation of the concept.
If the text representation is called 4 times for tnm classification its text representation will be:
not ( not ( not ( not ( tnm classification) ) ) )
Each time the method is called a "not" is added to the front of the text representation of the concept. If the text representation is called 4 times for tnm classification its text representation will be: not ( not ( not ( not ( tnm classification) ) ) )
I suggest to change it to