text: package pflag
  
  import (
  	"fmt"
  	"net"
  	"strings"
  )
  
  // -- net.IP value
  type ipValue net.IP
  
  func newIPValue(val net.IP, p *net.IP) *ipValue {
  	*p = val
  	return (*ipValue)(p)
  }
  
  func (i *ipValue) String() string { return net.IP(*i).String() }
  func (i *ipValue) Set(s string) error {
  	ip := net.ParseIP(strings.TrimSpace(s))
  	if ip == nil {
  		return fmt.Errorf("failed to parse IP: %q", s)
  	}
  	*i = ipValue(ip)
  	return nil
  }
  
  func (i *ipValue) Type() string {
  	return "ip"
  }
  
  func ipConv(sval string) (interface{}, error) {
  	ip := net.ParseIP(sval)
  	if ip != nil {
  		return ip, nil
  	}
  	return nil, fmt.Errorf("invalid string being converted to IP address: %s", sval)
  }
  
  // GetIP return the net.IP value of a flag with the given name
  func (f *FlagSet) GetIP(name string) (net.IP, error) {
  	val, err := f.getFlagType(name, "ip", ipConv)
  	if err != nil {
  		return nil, err
  	}
  	return val.(net.IP), nil
  }
  
  // IPVar defines an net.IP flag with specified name, default value, and usage string.
  // The argument p points to an net.IP variable in which to store the value of the flag.
  func (f *FlagSet) IPVar(p *net.IP, name string, value net.IP, usage string) {
  	f.VarP(newIPValue(value, p), name, "", usage)
  }
  
  // IPVarP is like IPVar, but accepts a shorthand letter that can be used after a single dash.
  func (f *FlagSet) IPVarP(p *net.IP, name, shorthand string, value net.IP, usage string) {
  	f.VarP(newIPValue(value, p), name, shorthand, usage)
  }
  
  // IPVar defines an net.IP flag with specified name, default value, and usage string.
  // The argument p points to an net.IP variable in which to store the value of the flag.
  func IPVar(p *net.IP, name string, value net.IP, usage string) {
  	CommandLine.VarP(newIPValue(value, p), name, "", usage)
  }
  
  // IPVarP is like IPVar, but accepts a shorthand letter that can be used after a single dash.
  func IPVarP(p *net.IP, name, shorthand string, value net.IP, usage string) {
  	CommandLine.VarP(newIPValue(value, p), name, shorthand, usage)
  }
  
  // IP defines an net.IP flag with specified name, default value, and usage string.
  // The return value is the address of an net.IP variable that stores the value of the flag.
  func (f *FlagSet) IP(name string, value net.IP, usage string) *net.IP {
  	p := new(net.IP)
  	f.IPVarP(p, name, "", value, usage)
  	return p
  }
  
  // IPP is like IP, but accepts a shorthand letter that can be used after a single dash.
  func (f *FlagSet) IPP(name, shorthand string, value net.IP, usage string) *net.IP {
  	p := new(net.IP)
  	f.IPVarP(p, name, shorthand, value, usage)
  	return p
  }
  
  // IP defines an net.IP flag with specified name, default value, and usage string.
  // The return value is the address of an net.IP variable that stores the value of the flag.
  func IP(name string, value net.IP, usage string) *net.IP {
  	return CommandLine.IPP(name, "", value, usage)
  }
  
  // IPP is like IP, but accepts a shorthand letter that can be used after a single dash.
  func IPP(name, shorthand string, value net.IP, usage string) *net.IP {
  	return CommandLine.IPP(name, shorthand, value, usage)
  }
  