T17e.hs:8:1: warning: [-Wunused-top-binds (in -Wextra, -Wunused-binds)]
    Defined but not used: ‘top’

T17e.hs:11:11: warning: [GHC-61367] [-Wunused-pattern-binds (in -Wextra, -Wunused-binds)]
    This pattern-binding binds no variables: True = True

T17e.hs:17:12: warning: [-Wunused-local-binds (in -Wextra, -Wunused-binds)]
    Defined but not used: ‘local’