switch e := e.(type) {
	case *ast.BinaryExpr:
		if int(e.Op) < len(op2str2) {
			return op2str2[e.Op]
		}
	case *ast.UnaryExpr:
		if int(e.Op) < len(op2str1) {
			return op2str1[e.Op]
		}
	}
	return ""
}

var op2str1 = [...]string{
	token.XOR: "bitwise complement",
}

// This is only used for operations that may cause overflow.
var op2str2 = [...]string{
	token.ADD: "addition",

		op := int(e.Op)
		if e.Y == nil {
			if op < len(op2str1) {
				return op2str1[op]
			}
		} else {
			if op < len(op2str2) {
				return op2str2[op]
			}
		}
	}
	return ""
}

var op2str1 = [...]string{
	syntax.Xor: "bitwise complement",
}

// This is only used for operations that may cause overflow.
var op2str2 = [...]string{
	syntax.Add: "addition",

                                      loc.loc.col_offset)
    else:
      return 'loc(unknown)'

  def _emit_with_loc(self, op_str, node=None):
    """Emit the mlir operation with the location associated with the node.

    Args:
      op_str: The mlir operation string to be emitted.
      node: The node of the AST tree, the mlir operation translated from.
    """
    loc = ''
    if node: