SOURCE_FILE
  FN
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "f"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE " "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          WILDCARD_PAT
            UNDERSCORE "_"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          CAST_EXPR
            REF_EXPR
              AMP "&"
              LITERAL
                INT_NUMBER "1"
            WHITESPACE " "
            AS_KW "as"
            WHITESPACE " "
            PTR_TYPE
              STAR "*"
              CONST_KW "const"
              WHITESPACE " "
              PATH_TYPE
                PATH
                  PATH_SEGMENT
                    NAME_REF
                      IDENT "i32"
          SEMICOLON ";"
        WHITESPACE " "
        R_CURLY "}"
  WHITESPACE "\n"
