this code stops when the user presses the 'q' key
the only chars accepted are the brain chars | tabs and spaces

+ add one to the 0th cell to start the while
[ while (true)
  , read input at 1st cell

  >[-] clean 2nd cell

  make letter 'q' before copying at 3rd cell
  ++++++++++>+++++++++++*+++

  <[-] go back to 2nd cell and clean it

  +* copy value from 1st to 2nd cell

  >% go to 3rd cell mod 2nd cell

  ?
    [-]<< if the value is not zero clean the cell and move to 1st cell
  :
    !
  ;
]