If no operator Name with associativity Associativity is visible from the context module, error 72 is raised.
If Associativity is not one of following atoms, a range error is raised:
---------------------------- xfx infix xfy infix yfx infix fx prefix fy prefix xf postfix yf postfix
Success:
      [eclipse]: op(100, fx, -+-).
      yes. % defined a global prefix operator
      [eclipse]: local_op(0, fy, -+-).
      yes. % hide any global prefix operator
      [eclipse]: current_op(X, Y, -+-).
      no (more) solution.
      [eclipse]: abolish_op(-+-, fy).
      yes. % remove the hiding
      [eclipse]: current_op(X, Y, -+-).
      X = 100
      Y = fx     More? (;)  % global visible again
      no (more) solution.
      [eclipse]: abolish_op(-+-, fx).
      yes. % remove the global definition
      [eclipse]: current_op(X, Y, -+-).
      no (more) solution.
Error:
      abolish_op(X, yfx).         (Error 4)
      abolish_op(+, X).           (Error 4)
      abolish_op("+", yfx).       (Error 5)
      abolish_op(+, 12).          (Error 5)
      abolish_op(+, fff).         (Error 6)
      abolish_op(no_op, fx).      (Error 72)
      local_op(100, fx, +),
          abolish_op(+, fy).      (Error 72).