SOURCE_FILE
  FN
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "main"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE "\n    "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          MACRO_PAT
            MACRO_CALL
              PATH
                PATH_SEGMENT
                  NAME_REF
                    IDENT "m"
              BANG "!"
              TOKEN_TREE
                L_PAREN "("
                IDENT "x"
                R_PAREN ")"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          LITERAL
            INT_NUMBER "0"
          SEMICOLON ";"
        WHITESPACE "\n"
        R_CURLY "}"
  WHITESPACE "\n"
