func NewShellProgramFunc(name string) ProgramFunc {
	return NewShellProgramFuncWithEnv(name, nil)
}
NewShellProgramFunc creates programs that are executed in a Shell.
package client
import (
	"fmt"
	"io"
	"os"
	"os/exec"
)
type Program interface {
	Output() ([]byte, error)
	Input(in io.Reader)
}
type ProgramFunc func(args ...string) Program