code: func (a *Assertions) FileExistsf(path string, msg string, args ...interface{}) {
  	if h, ok := a.t.(tHelper); ok {
  		h.Helper()
  	}
  	FileExistsf(a.t, path, msg, args...)
  }
docs: // FileExistsf checks whether a file exists in the given path. It also fails if the path points to a directory or there is an error when trying to check the file.