SOURCE_FILE
  FN
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "foo"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE "\n    "
        EXPR_STMT
          LOOP_EXPR
            LABEL
              LIFETIME
                LIFETIME_IDENT "'a"
              COLON ":"
            WHITESPACE " "
            LOOP_KW "loop"
            WHITESPACE " "
            BLOCK_EXPR
              STMT_LIST
                L_CURLY "{"
                R_CURLY "}"
        WHITESPACE "\n    "
        EXPR_STMT
          WHILE_EXPR
            LABEL
              LIFETIME
                LIFETIME_IDENT "'b"
              COLON ":"
            WHITESPACE " "
            WHILE_KW "while"
            WHITESPACE " "
            LITERAL
              TRUE_KW "true"
            WHITESPACE " "
            BLOCK_EXPR
              STMT_LIST
                L_CURLY "{"
                R_CURLY "}"
        WHITESPACE "\n    "
        FOR_EXPR
          LABEL
            LIFETIME
              LIFETIME_IDENT "'c"
            COLON ":"
          WHITESPACE " "
          FOR_KW "for"
          WHITESPACE " "
          IDENT_PAT
            NAME
              IDENT "x"
          WHITESPACE " "
          IN_KW "in"
          WHITESPACE " "
          TUPLE_EXPR
            L_PAREN "("
            R_PAREN ")"
          WHITESPACE " "
          BLOCK_EXPR
            STMT_LIST
              L_CURLY "{"
              R_CURLY "}"
        WHITESPACE "\n"
        R_CURLY "}"
  WHITESPACE "\n"
