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
          WHILE_EXPR
            WHILE_KW "while"
            WHITESPACE " "
            LITERAL
              TRUE_KW "true"
            WHITESPACE " "
            BLOCK_EXPR
              STMT_LIST
                L_CURLY "{"
                R_CURLY "}"
          SEMICOLON ";"
        WHITESPACE "\n    "
        EXPR_STMT
          WHILE_EXPR
            WHILE_KW "while"
            WHITESPACE " "
            LET_EXPR
              LET_KW "let"
              WHITESPACE " "
              TUPLE_STRUCT_PAT
                PATH
                  PATH_SEGMENT
                    NAME_REF
                      IDENT "Some"
                L_PAREN "("
                IDENT_PAT
                  NAME
                    IDENT "x"
                R_PAREN ")"
              WHITESPACE " "
              EQ "="
              WHITESPACE " "
              METHOD_CALL_EXPR
                PATH_EXPR
                  PATH
                    PATH_SEGMENT
                      NAME_REF
                        IDENT "it"
                DOT "."
                NAME_REF
                  IDENT "next"
                ARG_LIST
                  L_PAREN "("
                  R_PAREN ")"
            WHITESPACE " "
            BLOCK_EXPR
              STMT_LIST
                L_CURLY "{"
                R_CURLY "}"
          SEMICOLON ";"
        WHITESPACE "\n    "
        EXPR_STMT
          WHILE_EXPR
            WHILE_KW "while"
            WHITESPACE " "
            BLOCK_EXPR
              STMT_LIST
                L_CURLY "{"
                WHITESPACE " "
                LITERAL
                  TRUE_KW "true"
                WHITESPACE " "
                R_CURLY "}"
            WHITESPACE " "
            BLOCK_EXPR
              STMT_LIST
                L_CURLY "{"
                R_CURLY "}"
          SEMICOLON ";"
        WHITESPACE "\n"
        R_CURLY "}"
  WHITESPACE "\n"
