You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: utils.go
    path of file: ./repos/corteza/extra/server-discovery/vendor/github.com/go-chi/cors
    
    the code of the file until where you have to start completion: package cors

import "strings"

const toLower = 'a' - 'A'

type converter func(string) string

type wildcard struct {
	prefix string
	suffix string
}

func (w wildcard) match(s string) bool {
	return len(s) >= len(w.prefix+w.suffix) && strings.HasPrefix(s, w.prefix) && strings.HasSuffix(s, w.suffix)
}

// convert converts a list of string using the passed converter function
func convert(s []string, c converter) []string {
	out := []string{}
	for _, i := range s {
		out = append(out, c(i))
	}
	return out
}

// parseHeaderList tokenize + normalize a string containing a list of headers
func parseHeaderList(headerList string) []string {
	l := len(headerList)

    
func parseHeaderList(headerList string) []string {
	l := len(headerList)
	h := make([]byte, 0, l)
	upper := true
	// Estimate the number headers in order to allocate the right splice size
	t := 0
	for i := 0; i < l; i++ {
		if headerList[i] == ',' {
			t++
		}
	}
	headers := make([]string, 0, t)
	for i := 0; i < l; i++ {
		b := headerList[i]
		if b >= 'a' && b <= 'z' {
			if upper {
				h = append(h, b-toLower)
			} else {
				h = append(h, b)
			}
		} else if b >= 'A' && b <= 'Z' {
			if !upper {
				h = append(h, b+toLower)
			} else {
				h = append(h, b)
			}
		} else if b == '-' || b == '_' || b == '.' || (b >= '0' && b <= '9') {
			h = append(h, b)
		}

		if b == ' ' || b == ',' || i == l-1 {
			if len(h) > 0 {
				// Flush the found header
				headers = append(headers, string(h))
				h = h[:0]
				upper = true
			}
		} else {
			upper = b == '-'
		}
	}
	return headers
}