docs: public void setBody(AstNode body) {
          assertNotNull(body);
          this.body = body;
          if (Boolean.TRUE.equals(body.getProp(Node.EXPRESSION_CLOSURE_PROP))) {
              setIsExpressionClosure(true);
          }
          int absEnd = body.getPosition() + body.getLength();
          body.setParent(this);
          this.setLength(absEnd - this.position);
          setEncodedSourceBounds(this.position, absEnd);
      }