Few simple modifications to improve the readability and quality of the code.

[yj-yoo]

hi.
I'm going to make a few simple modifications to improve the readability and quality of the code.

• Simplify conditional expressions
  if var == true {}
  to
  if var {}

or

if err != nil { return false } return true
to
return err == nil

• Replacing deprecated packages
  ex) ioutil -> io

If there is any additional information, I will leave a comment.