extract common colWidth constant

usage.go

@@ -9,6 +9,9 @@ import (
 	"strings"
 )
 
+// the width of the left column
+const colWidth = 25
+
 // Fail prints usage information to stderr and exits with non-zero status
 func (p *Parser) Fail(msg string) {
 	p.WriteUsage(os.Stderr)
@@ -69,9 +72,6 @@ func (p *Parser) WriteHelp(w io.Writer) {
 
 	p.WriteUsage(w)
 
-	// the width of the left column
-	const colWidth = 25
-
 	// write the list of positionals
 	if len(positionals) > 0 {
 		fmt.Fprint(w, "\npositional arguments:\n")
@@ -101,7 +101,6 @@ func (p *Parser) WriteHelp(w io.Writer) {
 }
 
 func printOption(w io.Writer, spec *spec) {
-	const colWidth = 25
 	left := "  " + synopsis(spec, "--"+spec.long)
 	if spec.short != "" {
 		left += ", " + synopsis(spec, "-"+spec.short)