Persistent "import os"?

Traceback (most recent call last):
  File "/home/john/python/pystream/form1.py", line 82, in pushButton1_4_clicked
    os.popen('killall -9 mplayer')
NameError: global name 'os' is not defined

# Form implementation generated from reading ui file 'form1.ui'
#
# Created: Wed Jun 11 11:55:54 2003
#      by: The PyQt User Interface Compiler (pyuic)
#
# WARNING! All changes made in this file will be lost!


import sys
from qt import *


class Form1(QDialog):
    def __init__(self,parent = None,name = None,modal = 0,fl = 0):
        QDialog.__init__(self,parent,name,modal,fl)

        if not name:
            self.setName("Form1")



        self.pushButton1_2 = QPushButton(self,"pushButton1_2")
        self.pushButton1_2.setGeometry(QRect(30,50,91,21))

        self.pushButton1_3 = QPushButton(self,"pushButton1_3")
        self.pushButton1_3.setGeometry(QRect(30,80,91,21))

        self.pushButton1 = QPushButton(self,"pushButton1")
        self.pushButton1.setGeometry(QRect(30,20,91,21))

        self.pushButton5 = QPushButton(self,"pushButton5")
        self.pushButton5.setGeometry(QRect(171,20,60,21))

        self.pushButton5_2 = QPushButton(self,"pushButton5_2")
        self.pushButton5_2.setGeometry(QRect(171,50,60,21))

        self.pushButton1_4 = QPushButton(self,"pushButton1_4")
        self.pushButton1_4.setGeometry(QRect(140,80,91,21))
        self.pushButton1_4.setPaletteBackgroundColor(QColor(255,0,0))

        self.languageChange()

        self.resize(QSize(259,114).expandedTo(self.minimumSizeHint()))

        self.connect(self.pushButton1,SIGNAL("clicked()"),self.pushButton1_clicked)
        self.connect(self.pushButton1_2,SIGNAL("clicked()"),self.pushButton1_2_clicked)
        self.connect(self.pushButton1_3,SIGNAL("clicked()"),self.pushButton1_3_clicked)
        self.connect(self.pushButton1_4,SIGNAL("clicked()"),self.pushButton1_4_clicked)
        self.connect(self,SIGNAL("destroyed(QObject*)"),self.Form1_destroyed)

    def languageChange(self):
        self.setCaption(self.tr("PyStream"))
        self.pushButton1_2.setText(self.tr("977 - 80s"))
        self.pushButton1_3.setText(self.tr("Classical"))
        self.pushButton1.setText(self.tr("Techno"))
        self.pushButton5.setText(self.tr("Vol Up"))
        self.pushButton5_2.setText(self.tr("Vol Dn"))
        self.pushButton1_4.setText(self.tr("Stop"))

    def pushButton1_clicked(self):

        	os.popen('killall -9 mplayer')
        	os.popen('mplayer -cache 256 /usr/share/media/audio/streams/techno.pls &')
        

    def pushButton1_2_clicked(self):

        	os.popen('killall -9 mplayer')
        	os.popen('mplayer -cache 256 /usr/share/media/audio/streams/977.pls &')
        	self.Form1.setCaption("PyStream - Playing 977 - 80s")
        

    def pushButton1_3_clicked(self):

        	os.popen('killall -9 mplayer')
        	os.popen('mplayer -cache 256 /usr/share/media/audio/streams/classical.pls &')
        	self.Form1.setCaption("PyStream - Playing Classical")
        

    def pushButton1_4_clicked(self):

        	os.popen('killall -9 mplayer')
        	self.Form1.setCaption("PyStream")
        

    def Form1_destroyed(self,a0):
        print "Form1.Form1_destroyed(QObject*): Not implemented yet"


if __name__ == "__main__":
    a = QApplication(sys.argv)
    QObject.connect(a,SIGNAL("lastWindowClosed()"),a,SLOT("quit()"))
    w = Form1()
    a.setMainWidget(w)
    w.show()
    a.exec_loop()

#!/usr/bin/env python

import sys,os
import form1

class gui(form1.Form1):
	pass

#!/usr/bin/env python

import sys,qt,os,gui

def main():

	# make the application object (it needs the list of arguments)
	app = qt.QApplication(sys.argv)

	# ensure the application ends when its last window is closed
	qt.QObject.connect(app,qt.SIGNAL('lastWindowClosed()'),app,qt.SLOT('quit()'))

	# let's see the form that lives in myform.py
	form = gui.gui()
	app.setMainWidget(form)
	form.show()
	app.exec_loop()
	


if __name__ == "__main__":
    main()