*** Error: numbers or strings may not be operators in c_op(...).
*** Error: numbers or strings may not be operators in c_op(...).
*** Error: numbers or strings may not be operators in c_op(...).
*** Error: bad operator kind 'xff'.
*** Error: precedence must range from 1 to 1200 in c_op(...).
*** Error: precedence must range from 1 to 1200 in c_op(...).
*** Error: precedence must range from 1 to 1200 in c_op(...).
*** Error: precedence must be a positive integer in c_op(...).
