STYLE: example for trailing comma & add includes guideline

STYLE

@@ -1,53 +1,65 @@
-- Braces are mandatory for all control flow
-- Nested indentation should be kept to a minimum
-- Empty lines should be placed between different kinds of statements:
+0. Braces are mandatory for all control flow, as it improves the visibility of
+   scope.
+1. Nested indentation should be kept to a minimum.
+2. Empty lines should be placed between different kinds of statements:
 
-int t;
+	int t;
 
-assert(io->bufuse > 0);
-assert(io->bufuse <= io->bs);
+	assert(io->bufuse > 0);
+	assert(io->bufuse <= io->bs);
 
-if ((t = write(io->fd, io->buf, io->bufuse)) < 0) {
-	io->error = errno;
-	t = 0;
-} else if (t > 0) {
-	memmove(io->buf, &(io->buf)[t], (io->bufuse -= t));
-}
+	if ((t = write(io->fd, io->buf, io->bufuse)) < 0) {
+		io->error = errno;
+		t = 0;
+	} else if (t > 0) {
+		memmove(io->buf, &(io->buf)[t], (io->bufuse -= t));
+	}
 
-io->bytes += t;
-io->prec  += (t > 0 && io->bufuse > 0);
-io->rec   += (t > 0 && io->bufuse == 0);
+	io->bytes += t;
+	io->prec  += (t > 0 && io->bufuse > 0);
+	io->rec   += (t > 0 && io->bufuse == 0);
 
-return io;
+	return io;
 
-- Cases in switch statements and matches in match statements should be indented
-  one level
-- In C, spaces should be placed in control flow statements after the keyword and
-  before the opening brace:
+3. Cases in switch statements and matches in match statements should be indented
+   one level
+4. In C, spaces should be placed in control flow statements after the keyword
+   and before the opening brace:
 
-for (i = 2; i < argc; ++i) {
+	for (i = 2; i < argc; ++i) {
 
-- If a function, a C control flow statement, or a Rust macro has arguments that
-  cause the statement to be broken into multiple lines, this should be done by
-  placing the arguments on a new line inside the parentheses: 
+5. If a function, a C control flow statement, or a Rust macro has arguments that
+   cause the statement to be broken into multiple lines, this should be done by
+   placing the arguments on a new line inside the parentheses: 
 
-let usage = format!(
-	"Usage: {} [-d delimiter] index command [args...]",
-	argv[0],
-);
+	let usage = format!(
+		"Usage: {} [-d delimiter] index command [args...]",
+		argv[0],
+	);
 
-- If Rust function arguments or fields are on their own lines, they should
-  always have a trailing comma.
+6. If Rust function arguments or fields are on their own lines, they should
+   always have a trailing comma:
 
-- If text is on the same line as a brace, spaces should be placed after an
-  opening curly brace and before a closing one:
+	return Err(EvaluationError {
+		message: format!("{}: Invalid token", i),
+		code: EX_DATAERR,
+	})
 
-use sysexits::{ EX_DATAERR, EX_IOERR, EX_UNAVAILABLE, EX_USAGE };
+7. If text is on the same line as a brace, spaces should be placed after an
+   opening curly brace and before a closing one:
 
-- If a control flow statement is short enough to be easily understood in a
-  glance, it may be placed on a single line:
+	use sysexits::{ EX_DATAERR, EX_IOERR, EX_UNAVAILABLE, EX_USAGE };
 
-if (!argc < 0) { usage(program_name); }
+8. If a control flow statement is short enough to be easily understood in a
+   glance, it may be placed on a single line:
+
+	if (!argc < 0) { usage(program_name); }
+
+9. In C, note everything you use from a library in a comment subsequent to its
+   #include statement:
+
+	#include <unistd.h> /* close(2), getopt(3), lseek(2), read(2), write(2),
+                         * optarg, optind, STDIN_FILENO, STDOUT_FILENO */
 
 --
 Copyright © 2024 Emma Tebibyte <emma@tebibyte.media>