LET_STMT@0..11
  LET_KW@0..3 "let"
  WHITESPACE@3..4 " "
  IDENT_PAT@4..5
    NAME@4..5
      IDENT@4..5 "x"
  WHITESPACE@5..6 " "
  EQ@6..7 "="
  WHITESPACE@7..8 " "
  LITERAL@8..10
    INT_NUMBER@8..10 "10"
  SEMICOLON@10..11 ";"