func envKeyEqual(a, b string) bool {
	if GOOS == "windows" { // case insensitive
		for i := 0; i < len(a); i++ {
			ca, cb := a[i], b[i]
			if ca == cb || lowerASCII(ca) == lowerASCII(cb) {
				continue
			}
			return false
		}
		return true
	}
	return a == b
}

func lowerASCII(c byte) byte {
	if 'A' <= c && c <= 'Z' {
		return c + ('a' - 'A')
	}
	return c
}

// _cgo_setenv should be an internal detail,

		if tokenEqual(trimOWS(v[:comma]), token) {
			return true
		}
		v = v[comma+1:]
	}
	return tokenEqual(trimOWS(v), token)
}

// lowerASCII returns the ASCII lowercase version of b.
func lowerASCII(b byte) byte {
	if 'A' <= b && b <= 'Z' {
		return b + ('a' - 'A')
	}
	return b
}

// tokenEqual reports whether t1 and t2 are equal, ASCII case-insensitively.

func lowerASCIIBytes(x []byte) {
	for i, b := range x {
		if 'A' <= b && b <= 'Z' {
			x[i] += 'a' - 'A'
		}
	}
}

// lowerASCII returns the ASCII lowercase version of b.
func lowerASCII(b byte) byte {
	if 'A' <= b && b <= 'Z' {
		return b + ('a' - 'A')
	}
	return b
}

// trimSpace returns x without any leading or trailing ASCII whitespace.

		expectRuntimeCost  uint64
	}{
		{
			name:               "lowerAscii",
			expr:               "'ABCDEFGHIJ abcdefghij'.lowerAscii()",
			expectEsimatedCost: checker.CostEstimate{Min: 3, Max: 3},
			expectRuntimeCost:  3,
		},
		{
			name:               "lowerAsciiEquals",
			expr:               "'ABCDEFGHIJ abcdefghij'.lowerAscii() == 'abcdefghij ABCDEFGHIJ'.lowerAscii()",
			expectEsimatedCost: checker.CostEstimate{Min: 7, Max: 9},

				"self.val1.substring(4, 10).trim() == 'takes'":     6,
				"self.val1.upperAscii() == 'ROOK TAKES 👑'":         6,
				"self.val1.lowerAscii() == 'rook takes 👑'":         6,
				"self.val1.lowerAscii() == self.val1.lowerAscii()": 10,
				// strings version 2
				"'%d %s %f %s %s'.format([1, 'abc', 1.0, duration('1m'), timestamp('2000-01-01T00:00:00.000Z')]) == '1 abc 1.000000 60s 2000-01-01T00:00:00Z'": 6,

		var cost uint64
		if len(args) > 0 {
			cost += traversalCost(args[0]) // these O(n) operations all cost roughly the cost of a single traversal
		}
		return &cost
	case "url", "lowerAscii", "upperAscii", "substring", "trim":
		if len(args) >= 1 {
			cost := uint64(math.Ceil(float64(actualSize(args[0])) * common.StringTraversalCostFactor))
			return &cost
		}
	case "replace", "split":

	if err != nil {
		return 0, &DNSError{Err: err.Error(), Name: network + "/" + service}
	}
	// Lowercase the C service name.
	for i, b := range cservice[:len(service)] {
		cservice[i] = lowerASCII(b)
	}
	var res *_C_struct_addrinfo
	gerrno, err := _C_getaddrinfo(nil, (*_C_char)(unsafe.Pointer(&cservice[0])), hints, &res)
	if gerrno != 0 {
		switch gerrno {
		case _C_EAI_SYSTEM:

			expectedCalcCost: 629160,
			setMaxElements:   10,
			expectedSetCost:  22,
		},
		{
			name: "extended library lowerAscii",
			schemaGenerator: func(max *int64) *schema.Structural {
				strType := withMaxLength(primitiveType("string", ""), max)
				strType = withRule(strType, "self.lowerAscii() == 'lower!'")
				return &strType
			},
			expectedCalcCost: 314575,
			setMaxElements:   10,

									Type:      "string",
									MaxLength: pointer.Int64(5),
								},
							},
							XValidations: apiextensions.ValidationRules{
								{
									Rule: "self.all(x, self.exists_one(y, x.lowerAscii() == y.lowerAscii()))",
								},
							},
						},
					},
				},
			},
		},
		{
			name: "x-kubernetes-validations rule invalidated by messageExpression exceeding per-CRD estimated cost limit",

				"self.val1.substring(5) == 'takes 👑'",
				"self.val1.substring(0, 4) == 'Rook'",
				"self.val1.substring(4, 10).trim() == 'takes'",
				"self.val1.upperAscii() == 'ROOK TAKES 👑'",
				"self.val1.lowerAscii() == 'rook takes 👑'",

				"'%d %s %f %s %s'.format([1, 'abc', 1.0, duration('1m'), timestamp('2000-01-01T00:00:00.000Z')]) == '1 abc 1.000000 60s 2000-01-01T00:00:00Z'",
				"'%e'.format([3.14]) == '3.140000 × 10⁰⁰'",