Error in 13 = cordf13 13 invalid do_set left-hand side to assignment

This error message is indicating that there is an issue with attempting to assign a value to an invalid left-hand side. In this case, it is likely that the code is trying to assign a value to the output of the cor() function, which is not allowed.

To fix this error, you may need to review the code and ensure that any assignments are being made to valid objects. Additionally, you may want to check the syntax of any functions being used to ensure that they are being called correctly.