>= is not working

In line number 26 of allowing_compiler.py, I replaced + operator with >= which results into following exception.
"grako.exceptions.FailedPattern: (1:4) expecting '[-+]?[0-9]*\\.?[0-9]+([eE][-+]?[0-9]+)?' :
a >= b
   ^
NUMBER
atom
power
factor
term
arith_expr
shift_expr
and_expr
or_expr
comparison
not_test
and_test
or_test
test
arithmetic_expression"