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Source with the whole alphabet in order of appearance

The challenge is to write as short a source as possible, which contains and iterates through the whole English alphabet `"abcdefghijklmnopqrstuvwxyz"` in order from top to bottom. The first mentioning of the next expected letter is the only one that counts. If a letter appears earlier on than expected, then it does not count.

That is: if the letter `a` is the next expected letter, then in the source `b;abs;c;` the `a` counts and everything before it is ignored. The next expected letter in the alphabet is `b`, which is found immediately as the next letter in `abs`. That a `b` existed earlier on in the source has no relevance. Similarly, the `s` at the end of `abs` fills no purpose as the next expected letter is now `c`. And so on, until the whole alphabet has been found in the source.

- Identifiers, variable/function names, string literals or anything else that can be named by the programmer _do not count_ towards iterating through the alphabet.
- Only keywords, function names, constants or identifiers provided by the language's standard/default libraries count. 
- A solution may use non-standard libraries in which case it becomes a separate "language x + library y" solution.
- The program need not do anything meaningful but must compile cleanly (no language syntax or constraint violations etc) and execute without any crashes or exceptions thrown.
- Function-only answers are accepted and encouraged.
- Any library includes at the top of the program are free and do not count towards the total (if using tio.run, put such in the header section).
- The challenge is case-insensitive, accepting both upper and lower case letters.
- This is code golf, the shortest source that fulfil the requirements wins.

Non-golfed example of a correct solution in standard C:

# [C (gcc)], 217 bytes

<!-- language-all: lang-c -->

    void func (void)
    {
      fabs;cos;
      #define x long
      acosh;
      printf("hello world");
      jmp_buf j;
      isblank;
      long _Atomic l;
      alignof(int);
      puts;
      qsort;qsort;
      NULL;
      (void)pow;
      fmax;
      INFINITY;
      sizeof j;
    }

[Try it online!][TIO-m0gtbfip]

[C (gcc)]: https://gcc.gnu.org/
[TIO-m0gtbfip]: https://tio.run/##ZZA9T8MwEIb3/IpTuyRDGGAMILFUilRlgoGpcvyRXHF8JnZoAfHbgy8dUMrie@955fuSZSflvEUn7aQ03IeokG76x@wPDSL2ayLjp9drpMfRXf0LOh4Hf8Wistj@Y8Ji5xKdPwgVmMlJyFkW2XcGYEQbKkmhSnqrtEGn4QyWXJeASEbPjh/RRZNvem0twYlGqzYFG2mIQzsZOHKCobXCvbHkAnB4ijSgBMtkGYNMngotP/0Ul6bvgcZYXd6UNi/7PcfLiJ5OnJhBnDnWza5u6udX1gG/NC2Nf@ZUEwaBbrVYWjQv2J3LdIUHeXs3l14r4SLKMp2UxvAL "C (gcc) – Try It Online"
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To go through this source, `func` is an identifier and does not contribute to the solution (but to the total amount of characters for code golf like usual). Neither does `x`, `"hello world"` etc. We find the alphabet as follows (bold text):


 > void func (void)
{
  f**ab**s;**c**os;
  #**def**ine x lon**g**
  acos**h**;
  pr**i**ntf("hello world");
  **j**mp_buf j;
  isblan**k**;
  **l**ong _Ato**m**ic l;
  alig**no**f(int);
  **p**uts;
  **q**so**r**t;q**s**or**t**;
  N**U**LL;
  (**v**oid)po**w**;
  fma**x**;
  INFINIT**Y**;
  si**z**eof j;
}