[ben@BlueDust ~]$ crystal eval
puts 'h'.to_u8
Unhandled exception: Invalid integer: h (ArgumentError)
  from /usr/share/crystal/src/char.cr:557:20 in 'to_i'
  from /usr/share/crystal/src/char.cr:598:3 in 'to_u8'
  from /eval:1:1 in '__crystal_main'
  from /usr/share/crystal/src/crystal/main.cr:106:5 in 'main_user_code'
  from /usr/share/crystal/src/crystal/main.cr:92:7 in 'main'
  from /usr/share/crystal/src/crystal/main.cr:115:3 in 'main'
  from __libc_start_main
  from _start
  from ???
[ben@BlueDust ~]$ crystal eval
puts 'h'.to_u8!
Showing last frame. Use --error-trace for full trace.

error in line 1
Error: undefined method 'to_u8!' for Cha