code: func (cl *CommandLine) RemoveFlagMatch(matchFn func(CommandLineFlag) bool) (found bool) {
  	newFlags := cl.Flags[:0]
  	for _, f := range cl.Flags {
  		if !matchFn(f) {
  			newFlags = append(newFlags, f)
  		} else {
  			found = true
  		}
  	}
  	cl.Flags = newFlags
  	return
  }
docs: // RemoveFlagMatch removes all instances of flags that match the selection
  // function.
  //
  // matchFn is a function that accepts a candidate flag and returns true if it
  // should be removed, false if it should not.