def concept one as 1
def concept two as 2
def concept three as 3
def concept four as 4
def concept five as 5
def concept six as 6
def concept seven as 7
def concept eight as 8
def concept nine as 9
def concept ten as 10
def concept eleven as 11
def concept twelve as 12
def concept thirteen as 13
def concept fourteen as 14
def concept fifteen as 15
def concept sixteen as 16
def concept seventeen as 17
def concept eighteen as 18
def concept nineteen as 19
def concept twenty as 20
def concept number
one isa number
two isa number
three isa number
four isa number
five isa number
six isa number
seven isa number
eight isa number
nine isa number
ten isa number
eleven isa number
twelve isa number
thirteen isa number
fourteen isa number
fifteen isa number
sixteen isa number
seventeen isa number
eighteen isa number
nineteen isa number
twenty isa numberdef concept twenties from bnf twenty number where number < 10 as twenty + number