How to use the qtpy.QtCore.QSize function in QtPy

self.tabWidget.addTab(self.Generate, "")
        self.Batch = QtWidgets.QWidget()
        self.Batch.setObjectName("Batch")
        self.gridLayout_3 = QtWidgets.QGridLayout(self.Batch)
        self.gridLayout_3.setContentsMargins(21, 21, 21, 5)
        self.gridLayout_3.setObjectName("gridLayout_3")
        self.label_5 = QtWidgets.QLabel(self.Batch)
        self.label_5.setAlignment(QtCore.Qt.AlignRight|QtCore.Qt.AlignTrailing|QtCore.Qt.AlignVCenter)
        self.label_5.setObjectName("label_5")
        self.gridLayout_3.addWidget(self.label_5, 1, 0, 1, 1)
        self.batch_wave = QtWidgets.QLineEdit(self.Batch)
        self.batch_wave.setObjectName("batch_wave")
        self.gridLayout_3.addWidget(self.batch_wave, 1, 1, 1, 6)
        self.batchProcessButton = QtWidgets.QPushButton(self.Batch)
        self.batchProcessButton.setEnabled(True)
        self.batchProcessButton.setMinimumSize(QtCore.QSize(0, 40))
        font = QtGui.QFont()
        font.setKerning(True)
        self.batchProcessButton.setFont(font)
        self.batchProcessButton.setAutoDefault(False)
        self.batchProcessButton.setObjectName("batchProcessButton")
        self.gridLayout_3.addWidget(self.batchProcessButton, 7, 1, 1, 6)
        self.label_24 = QtWidgets.QLabel(self.Batch)
        self.label_24.setAlignment(QtCore.Qt.AlignRight|QtCore.Qt.AlignTrailing|QtCore.Qt.AlignVCenter)
        self.label_24.setObjectName("label_24")
        self.gridLayout_3.addWidget(self.label_24, 6, 0, 1, 1)
        self.label_22 = QtWidgets.QLabel(self.Batch)
        self.label_22.setAlignment(QtCore.Qt.AlignRight|QtCore.Qt.AlignTrailing|QtCore.Qt.AlignVCenter)
        self.label_22.setObjectName("label_22")
        self.gridLayout_3.addWidget(self.label_22, 5, 2, 1, 1)
        self.label_19 = QtWidgets.QLabel(self.Batch)
        self.label_19.setAlignment(QtCore.Qt.AlignRight|QtCore.Qt.AlignTrailing|QtCore.Qt.AlignVCenter)

Form.resize(468, 45)

        self.gridLayout = QtWidgets.QGridLayout(Form)
        self.gridLayout.setObjectName("gridLayout")
        self.horizontalLayout = QtWidgets.QHBoxLayout()
        self.horizontalLayout.setObjectName("horizontalLayout")

        self.loadCurrentRunButton = QtWidgets.QPushButton(Form)
        self.loadCurrentRunButton.setText("Load Current Run")
        self.loadCurrentRunButton.setMinimumSize(QtCore.QSize(100, 25))
        self.loadCurrentRunButton.setToolTip("Load the current run for the current instrument")
        self.loadCurrentRunButton.setObjectName("loadCurrentRunButton")

        self.incrementRunButton = QtWidgets.QToolButton(Form)
        self.incrementRunButton.setText(">")
        self.incrementRunButton.setMinimumSize(QtCore.QSize(25, 25))
        self.incrementRunButton.setToolTip("Increment the run")
        self.incrementRunButton.setObjectName("incrementRunButton")

        self.decrementRunButton = QtWidgets.QToolButton(Form)
        self.decrementRunButton.setText("<")
        self.decrementRunButton.setMinimumSize(QtCore.QSize(25, 25))
        self.decrementRunButton.setToolTip("Decrement the run")
        self.decrementRunButton.setObjectName("decrementRunButton")

        self.instrumentLabel = QtWidgets.QLabel(Form)
        self.instrumentLabel.setText("Instrument")
        self.instrumentLabel.setToolTip("")
        self.instrumentLabel.setObjectName("instrumentLabel")

        self.runEdit = QtWidgets.QLineEdit(Form)
        self.runEdit.setMinimumSize(QtCore.QSize(0, 25))

def setup_tool_bar(self):
        '''
        Setup the top tool bar
        '''
        self.tool_bar = QToolBar(self.public)
        self.tool_bar.setObjectName("dockWidgetToolBar")
        self.layout.insertWidget(0, self.tool_bar)
        self.tool_bar.setIconSize(QSize(16, 16))
        self.tool_bar.toggleViewAction().setEnabled(False)
        self.tool_bar.toggleViewAction().setVisible(False)
        self.public.top_level_changed.connect(self.public.set_toolbar_floating_style)

def minimumSizeHint(self):
        """
        This property holds the recommended minimum size for the widget.

        Returns
        -------
        QSize
        """
        return QSize(10, 10)  # This is totally arbitrary, I just want *some* visible nonzero size

sizePolicy.setVerticalStretch(0)
        sizePolicy.setHeightForWidth(self.search_lineEdit.sizePolicy().hasHeightForWidth())
        self.search_lineEdit.setSizePolicy(sizePolicy)
        self.search_lineEdit.setMinimumSize(QtCore.QSize(75, 0))
        self.search_lineEdit.setMaximumSize(QtCore.QSize(90, 16777215))
        self.search_lineEdit.setMaxLength(20)
        self.search_lineEdit.setObjectName("search_lineEdit")
        self.horizontalLayout.addWidget(self.search_lineEdit)
        self.search_btn = QtWidgets.QPushButton(self.centralwidget)
        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Fixed, QtWidgets.QSizePolicy.Fixed)
        sizePolicy.setHorizontalStretch(0)
        sizePolicy.setVerticalStretch(0)
        sizePolicy.setHeightForWidth(self.search_btn.sizePolicy().hasHeightForWidth())
        self.search_btn.setSizePolicy(sizePolicy)
        self.search_btn.setMinimumSize(QtCore.QSize(40, 0))
        self.search_btn.setMaximumSize(QtCore.QSize(30, 16777215))
        self.search_btn.setObjectName("search_btn")
        self.horizontalLayout.addWidget(self.search_btn)
        self.gridLayout.addLayout(self.horizontalLayout, 1, 0, 1, 1)
        self.horizontalLayout_4 = QtWidgets.QHBoxLayout()
        self.horizontalLayout_4.setObjectName("horizontalLayout_4")
        self.staDate_label = QtWidgets.QLabel(self.centralwidget)
        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Preferred)
        sizePolicy.setHorizontalStretch(0)
        sizePolicy.setVerticalStretch(0)
        sizePolicy.setHeightForWidth(self.staDate_label.sizePolicy().hasHeightForWidth())
        self.staDate_label.setSizePolicy(sizePolicy)
        self.staDate_label.setMinimumSize(QtCore.QSize(80, 0))
        self.staDate_label.setMaximumSize(QtCore.QSize(90, 16777215))
        self.staDate_label.setObjectName("staDate_label")
        self.horizontalLayout_4.addWidget(self.staDate_label)
        self.label_2 = QtWidgets.QLabel(self.centralwidget)

def sizeHint(self):
        return QSize(0, 0)

def __init__(self, parent=None, filename=None):
        QPushButton.__init__(self, parent)
        PyDMPrimitiveWidget.__init__(self)
        self.mouseReleaseEvent = self.push_button_release_event
        self.setContextMenuPolicy(Qt.CustomContextMenu)
        self.customContextMenuRequested.connect(self.show_context_menu)

        self.iconFont = IconFont()
        self._icon = self.iconFont.icon("file")
        self.setIconSize(QSize(16, 16))
        self.setIcon(self._icon)

        self._filenames = [filename] if filename is not None else []
        self._titles = []
        self._macros = []
        self.num_additional_items = 0
        self._shift_key_was_down = False
        self.setCursor(QCursor(self._icon.pixmap(16, 16)))
        self._display_menu_items = None
        self._display_filename = ""
        self._macro_string = None
        self._open_in_new_window = False
        self.open_in_new_window_action = QAction("Open in New Window", self)
        self.open_in_new_window_action.triggered.connect(partial(self.open_display, target=self.NEW_WINDOW))
        self._show_icon = True
        self._menu_needs_rebuild = True

def create_button(text='', layout=None, tooltip=None, icon=None,
                  enabled=True, default=False):
    """Create a button, set its title, and add it to the parent."""
    button = QtWidgets.QPushButton()
    button.setCursor(Qt.PointingHandCursor)
    button.setFocusPolicy(Qt.NoFocus)
    if text:
        button.setText(' ' + text)
    if icon is not None:
        button.setIcon(icon)
        button.setIconSize(QtCore.QSize(defs.small_icon, defs.small_icon))
    if tooltip is not None:
        button.setToolTip(tooltip)
    if layout is not None:
        layout.addWidget(button)
    if not enabled:
        button.setEnabled(False)
    if default:
        button.setDefault(True)
    return button

def __init__(self, parent=None):
        super(GraphView, self).__init__(parent)
        self.setObjectName('graphView')

        self.__graphViewWidget = parent

        self.setRenderHint(QtGui.QPainter.Antialiasing)
        self.setRenderHint(QtGui.QPainter.TextAntialiasing)

        self.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)
        self.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)

        # Explicitly set the scene rect. This ensures all view parameters will be explicitly controlled
        # in the event handlers of this class.
        size = QtCore.QSize(600, 400);
        self.resize(size)
        self.setSceneRect(-size.width() * 0.5, -size.height() * 0.5, size.width(), size.height())

        self.setAcceptDrops(True)
        self.reset()

def event(self, event):
        res = QtWidgets.QMessageBox.event(self, event)
        event_type = event.type()
        if (event_type == QtCore.QEvent.MouseMove or
                event_type == QtCore.QEvent.MouseButtonPress):
            maxi = QtCore.QSize(defs.max_size, defs.max_size)
            self.setMaximumSize(maxi)
            text = self.findChild(QtWidgets.QTextEdit)
            if text is not None:
                expand = QtWidgets.QSizePolicy.Expanding
                text.setSizePolicy(QtWidgets.QSizePolicy(expand, expand))
                text.setMaximumSize(maxi)
        return res