func (t *Template) ParseFS(tfs TrustedFS, patterns ...string) (*Template, error) {
	return parseFS(t, tfs.fsys, patterns)
}
ParseFS is like ParseFiles or ParseGlob but reads from the TrustedFS
instead of the host operating system's file system.
It accepts a list of glob patterns.
(Note that most file names serve as glob patterns matching only themselves.)
package template
import (
	"embed"
	"fmt"
	"io/fs"
	"os"
	"path"
)
type TrustedFS struct {
	fsys fs.FS
}
func TrustedFSFromEmbed(fsys embed.FS) TrustedFS {
	return TrustedFS{fsys: fsys}
}
func TrustedFSFromTrustedSource(ts TrustedSource) TrustedFS {
	return TrustedFS{fsys: os.DirFS(ts.src)}
}
func ParseFS(tfs TrustedFS, patterns ...string) (*Template, error) {
	return parseFS(nil, tfs.fsys, patterns)
}