text: package pflag
  
  import (
  	"fmt"
  	"net"
  	"strings"
  )
  
  // IPNet adapts net.IPNet for use as a flag.
  type ipNetValue net.IPNet
  
  func (ipnet ipNetValue) String() string {
  	n := net.IPNet(ipnet)
  	return n.String()
  }
  
  func (ipnet *ipNetValue) Set(value string) error {
  	_, n, err := net.ParseCIDR(strings.TrimSpace(value))
  	if err != nil {
  		return err
  	}
  	*ipnet = ipNetValue(*n)
  	return nil
  }
  
  func (*ipNetValue) Type() string {
  	return "ipNet"
  }
  
  func newIPNetValue(val net.IPNet, p *net.IPNet) *ipNetValue {
  	*p = val
  	return (*ipNetValue)(p)
  }
  
  func ipNetConv(sval string) (interface{}, error) {
  	_, n, err := net.ParseCIDR(strings.TrimSpace(sval))
  	if err == nil {
  		return *n, nil
  	}
  	return nil, fmt.Errorf("invalid string being converted to IPNet: %s", sval)
  }
  
  // GetIPNet return the net.IPNet value of a flag with the given name
  func (f *FlagSet) GetIPNet(name string) (net.IPNet, error) {
  	val, err := f.getFlagType(name, "ipNet", ipNetConv)
  	if err != nil {
  		return net.IPNet{}, err
  	}
  	return val.(net.IPNet), nil
  }
  
  // IPNetVar defines an net.IPNet flag with specified name, default value, and usage string.
  // The argument p points to an net.IPNet variable in which to store the value of the flag.
  func (f *FlagSet) IPNetVar(p *net.IPNet, name string, value net.IPNet, usage string) {
  	f.VarP(newIPNetValue(value, p), name, "", usage)
  }
  
  // IPNetVarP is like IPNetVar, but accepts a shorthand letter that can be used after a single dash.
  func (f *FlagSet) IPNetVarP(p *net.IPNet, name, shorthand string, value net.IPNet, usage string) {
  	f.VarP(newIPNetValue(value, p), name, shorthand, usage)
  }
  
  // IPNetVar defines an net.IPNet flag with specified name, default value, and usage string.
  // The argument p points to an net.IPNet variable in which to store the value of the flag.
  func IPNetVar(p *net.IPNet, name string, value net.IPNet, usage string) {
  	CommandLine.VarP(newIPNetValue(value, p), name, "", usage)
  }
  
  // IPNetVarP is like IPNetVar, but accepts a shorthand letter that can be used after a single dash.
  func IPNetVarP(p *net.IPNet, name, shorthand string, value net.IPNet, usage string) {
  	CommandLine.VarP(newIPNetValue(value, p), name, shorthand, usage)
  }
  
  // IPNet defines an net.IPNet flag with specified name, default value, and usage string.
  // The return value is the address of an net.IPNet variable that stores the value of the flag.
  func (f *FlagSet) IPNet(name string, value net.IPNet, usage string) *net.IPNet {
  	p := new(net.IPNet)
  	f.IPNetVarP(p, name, "", value, usage)
  	return p
  }
  
  // IPNetP is like IPNet, but accepts a shorthand letter that can be used after a single dash.
  func (f *FlagSet) IPNetP(name, shorthand string, value net.IPNet, usage string) *net.IPNet {
  	p := new(net.IPNet)
  	f.IPNetVarP(p, name, shorthand, value, usage)
  	return p
  }
  
  // IPNet defines an net.IPNet flag with specified name, default value, and usage string.
  // The return value is the address of an net.IPNet variable that stores the value of the flag.
  func IPNet(name string, value net.IPNet, usage string) *net.IPNet {
  	return CommandLine.IPNetP(name, "", value, usage)
  }
  
  // IPNetP is like IPNet, but accepts a shorthand letter that can be used after a single dash.
  func IPNetP(name, shorthand string, value net.IPNet, usage string) *net.IPNet {
  	return CommandLine.IPNetP(name, shorthand, value, usage)
  }
  