Accessing Widgets from ui.py module

[jftichett56]

I'm not sure why im going brain dead on this. I've tried for two days and it should be dirt simple but I think I an not getting something about class and variable visibility. Per every tutorial out there i want to keep the gui seperate from the main code. So following example I created hello world ui.
@

from PyQt4 import QtCore, QtGui

try:
_fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
def _fromUtf8(s):
return s

try:
_encoding = QtGui.QApplication.UnicodeUTF8
def _translate(context, text, disambig):
return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
def _translate(context, text, disambig):
return QtGui.QApplication.translate(context, text, disambig)

class Ui_MainWindow(object):
def setupUi(self, MainWindow):
MainWindow.setObjectName(_fromUtf8("MainWindow"))
MainWindow.resize(640, 480)
self.centralwidget = QtGui.QWidget(MainWindow)
self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
self.label1 = QtGui.QLabel(self.centralwidget)
self.label1.setGeometry(QtCore.QRect(190, 210, 251, 111))
font = QtGui.QFont()
font.setPointSize(24)
self.label1.setFont(font)
self.label1.setObjectName(_fromUtf8("label1"))
self.lcd1 = QtGui.QLCDNumber(self.centralwidget)
self.lcd1.setGeometry(QtCore.QRect(210, 30, 241, 111))
self.lcd1.setObjectName(_fromUtf8("lcd1"))
MainWindow.setCentralWidget(self.centralwidget)
self.menubar = QtGui.QMenuBar(MainWindow)
self.menubar.setGeometry(QtCore.QRect(0, 0, 640, 21))
self.menubar.setObjectName(_fromUtf8("menubar"))
MainWindow.setMenuBar(self.menubar)
self.statusbar = QtGui.QStatusBar(MainWindow)
self.statusbar.setObjectName(_fromUtf8("statusbar"))
MainWindow.setStatusBar(self.statusbar)

    self.retranslateUi(MainWindow)
    QtCore.QMetaObject.connectSlotsByName(MainWindow)

def retranslateUi(self, MainWindow):
    MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow", None))
    self.label1.setText(_translate("MainWindow", "Hello World", None))

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And Main file as:

#!/usr/bin/env python
import sys
from helloworld import *
app = QtGui.QApplication(sys.argv)
MainWindow = QtGui.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
sys.exit(app.exec_())
==== all the below and same with label fail saying lcd1 or label1 are not members of (whatever i prepended)
lcd1.display='999'
ui.lcd1.display='999'
Ui_MainWindow.lcd1.display = '999'

===============================================
@

and that runs file. However, I would like to change, say the value of the lcd or label now.
and all attempts at referencing them say they are not part of ?
I've left the attempts above as comments.
Also, and this is silly, would code go after sys.exec or after mainwindow.show or???

Im fluent in a lot of languages but for some reason im not understanding this.
Thanks for any guidance.
p.s. Comments in code '#' got turned into numbered lines so i took them out. am i posting wrong?

[edit: added missing coding tags @ SGaist]