anchor.diff:  Left     160 comp_expr_op.
   Left     170 add_op.
   Left     180 mult_op.
  -Right    190 and_concat_op.
   Right    200 addadd_op.
   Right    210 multmult_op.
   Left     260 dot_call_op.
  
positive.code: Right     40 when_op.
  Left      50 in_op.
  Left      60 pipe_op.
  Right     80 match_op.
  Right     90 arrow_op.
  Left     100 oror_op.
  
negative.code: matched_op_expr -> matched_expr and_op matched_expr : build_op('$2', '$1', '$3').
  matched_op_expr -> matched_expr or_op matched_expr : build_op('$2', '$1', '$3').
  matched_op_expr -> matched_expr pipe_op matched_expr : build_op('$2', '$1', '$3').
  matched_op_expr -> matched_expr and_pipe_op matched_expr : build_op('$2', '$1', '$3').
  matched_op_expr -> matched_expr in_op matched_expr : build_op('$2', '$1', '$3').
  matched_op_expr -> matched_expr when_op matched_expr : build_op('$2', '$1', '$3').
  matched_op_expr -> matched_expr arrow_op matched_expr : build_op('$2', '$1', '$3').
  