How to use the qtpy.QtWidgets.QPushButton function in QtPy

l = QtWidgets.QGridLayout()
        l.setContentsMargins(0, 0, 0, 0)
        l.setSpacing(0)
        l.addWidget(sc_w, 1, 0)
        l.addWidget(bg_w, 1, 1)
        l.addWidget(tmeas_bg_w, 2, 0)
        l.addWidget(tmeas_exp_w, 2, 1)
        self.layout.addLayout(l)

        ly = QtWidgets.QHBoxLayout()
        l.addLayout(ly, 0, 0, 1, 2)
        ly.addWidget(QtWidgets.QLabel('Background file:'))
        self.lineEdit = QtWidgets.QLineEdit()
        ly.addWidget(self.lineEdit)

        open_bg = QtWidgets.QPushButton()
        open_bg.setText('...')
        ly.addWidget(open_bg)

        self.background_select = ExperimentalDataSelector(
            parent=None,
            change_event=self.change_bg_curve,
            fit=self.fit
        )
        open_bg.clicked.connect(self.background_select.show)

        a = QtWidgets.QHBoxLayout()
        a.addWidget(QtWidgets.QLabel('nPh(Bg)'))
        self.lineedit_nphBg = QtWidgets.QLineEdit()
        a.addWidget(self.lineedit_nphBg)
        l.addLayout(a, 3, 0, 1, 1)

self.icase_vector_label = QLabel("iCase (Vector):")
        self.icase_vector_edit = QSpinBox(self)
        self.icase_vector_edit.setRange(1, icase_max)
        self.icase_vector_edit.setSingleStep(1)
        if self._icase_vector is not None:
            self.icase_vector_edit.setValue(self._icase_vector)

        self.scale_label = QLabel("True Scale:")
        self.scale_edit = QLineEdit(str(self._scale))
        self.scale_button = QPushButton("Default")
        self.scale_edit.setToolTip('Scale factor of the "deflection"')
        self.scale_button.setToolTip('Sets the scale factor of the gif to %s' % self._scale)

        self.arrow_scale_label = QLabel("Arrow Scale:")
        self.arrow_scale_edit = QLineEdit(str(self._scale))
        self.arrow_scale_button = QPushButton("Default")
        self.arrow_scale_edit.setToolTip('Scale factor of the "arrows"')
        self.arrow_scale_button.setToolTip('Sets the arrow scale factor of the gif to %s' % (
            self._arrow_scale))

        self.arrow_scale_label.setVisible(False)
        self.arrow_scale_edit.setVisible(False)
        self.arrow_scale_button.setVisible(False)

        self.time_label = QLabel("Total Time (sec):")
        self.time_edit = QDoubleSpinBox(self)
        self.time_edit.setValue(self._default_time)
        self.time_edit.setRange(0.1, 5. * 60.)
        self.time_edit.setDecimals(2)
        self.time_edit.setSingleStep(0.1)
        self.time_button = QPushButton("Default")
        self.time_edit.setToolTip("Total time of the gif")

self.setWindowTitle('Modify %s' % obj.type)
        self.grid_objs = grid_objs

        #self.create_widgets()
        #self.create_layout()
        #self.set_connections()
        desc_comment = QHBoxLayout()
        self.desc = QLabel('Description:')
        self.comment = QTextEdit(obj.comment.replace('\n', '<br>'))
        desc_comment.addWidget(self.desc)
        desc_comment.addWidget(self.comment)

        #-----------------------------------------------------------------------
        # closing
        self.apply_button = QPushButton("Apply")
        self.ok_button = QPushButton("OK")
        self.cancel_button = QPushButton("Cancel")
        #-----------------------------------------------------------------------

        ok_cancel_box = QHBoxLayout()
        ok_cancel_box.addWidget(self.apply_button)
        ok_cancel_box.addWidget(self.ok_button)
        ok_cancel_box.addWidget(self.cancel_button)

        vbox = QVBoxLayout()
        vbox.addLayout(grid)
        vbox.addLayout(desc_comment)
        #vbox.addLayout(hbox)
        vbox.addStretch()
        vbox.addLayout(ok_cancel_box)
        self.setLayout(vbox)

self.label_4.setSizePolicy(sizePolicy)
        self.label_4.setMaximumSize(QtCore.QSize(48, 16777215))
        self.label_4.setObjectName("label_4")
        self.horizontalLayout.addWidget(self.label_4)
        self.search_lineEdit = QtWidgets.QLineEdit(self.centralwidget)
        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Fixed)
        sizePolicy.setHorizontalStretch(0)
        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)

def __init__(self, parent, map):
        QtWidgets.QDialog.__init__(self, parent)
        main_layout = QtWidgets.QVBoxLayout(self)
        self.layout = QtWidgets.QHBoxLayout()
        main_layout.addLayout(self.layout)
        button_layout = QtWidgets.QHBoxLayout()
        main_layout.addLayout(button_layout)
        self.button_cancel = QtWidgets.QPushButton("Cancel")
        self.button_cancel.clicked.connect(lambda x: self.done(0))
        button_layout.addStretch()
        button_layout.addWidget(self.button_cancel)

        self.maps = plt.colormaps()
        self.buttons = []
        self.setWindowTitle("Select colormap")

        # Have colormaps separated into categories:
        # http://matplotlib.org/examples/color/colormaps_reference.html
        cmaps = [('Perceptually Uniform Sequential', [
            'viridis', 'plasma', 'inferno', 'magma']),
                 ('Sequential', [
                     'Greys', 'Purples', 'Blues', 'Greens', 'Oranges', 'Reds',
                     'YlOrBr', 'YlOrRd', 'OrRd', 'PuRd', 'RdPu', 'BuPu',
                     'GnBu', 'PuBu', 'YlGnBu', 'PuBuGn', 'BuGn', 'YlGn']),

'sub plane': [Data2D.sub_plane, [('x_slope', 0.0),
                                             ('y_slope', 0.0)]],
            'xderiv': [Data2D.xderiv, [('method', ['midpoint',
                                                   '2nd order central diff'])]],
            'yderiv': [Data2D.yderiv, [('method', ['midpoint',
                                                   '2nd order central diff'])]],
        }

        self.options = QtWidgets.QListWidget(self)
        self.options.addItems(sorted(self.items.keys()))
        self.options.currentItemChanged.connect(self.on_select_option)

        self.b_add = QtWidgets.QPushButton('Add')
        self.b_add.clicked.connect(self.on_add)

        self.b_up = QtWidgets.QPushButton('Up')
        self.b_up.clicked.connect(self.on_up)

        self.b_down = QtWidgets.QPushButton('Down')
        self.b_down.clicked.connect(self.on_down)

        self.b_remove = QtWidgets.QPushButton('Remove')
        self.b_remove.clicked.connect(self.on_remove)

        self.b_clear = QtWidgets.QPushButton('Clear')
        self.b_clear.clicked.connect(self.on_clear)

        self.b_update = QtWidgets.QPushButton('Update')
        self.b_update.clicked.connect(self.on_update)

        self.b_load = QtWidgets.QPushButton('Load...')
        self.b_load.clicked.connect(self.on_load)

def AddQColorChoose(layout, text, value=None, strech=False):
    # add a layout
    horizontal_layout = QtWidgets.QHBoxLayout()
    layout.addLayout(horizontal_layout)
    # add a text
    # text = QtWidgets.QLabel(text)
    button = QtWidgets.QPushButton("")

    # button.label = text

    def OpenDialog():
        # get new color from color picker
        qcolor = QtGui.QColor(*np.array(mpl.colors.to_rgb(button.getColor())) * 255)
        color = QtWidgets.QColorDialog.getColor(qcolor)
        # if a color is set, apply it
        if color.isValid():
            color = "#%02x%02x%02x" % color.getRgb()[:3]
            button.setColor(color)
            lineEdit.setText(color)
            try:
                button.color_changed(color)
            except AttributeError:
                pass

group_name = ["a", "b", "c"]
        self.ws0 = table_utils.addDoubleToTable(
            self.table, group_name[0], 0, 1)
        self.ws1 = table_utils.addDoubleToTable(
            self.table, group_name[1], 0, 2)
        self.ws2 = table_utils.addDoubleToTable(
            self.table, group_name[2], 0, 3)

        # row to describe a pair
        table_utils.setRowName(self.table, 1, "Pair")
        self.g1 = table_utils.addComboToTable(self.table, 1, group_name, 1)
        self.g2 = table_utils.addComboToTable(self.table, 1, group_name, 2)
        self.alpha = table_utils.addDoubleToTable(self.table, "2.", 1, 3)

        # explicit update button
        btn = QtWidgets.QPushButton("print context", self)

        # create grid
        self.grid.addWidget(self.table)
        self.grid.addWidget(btn)

        # add connections
        btn.clicked.connect(self.sendUpdateSignal)
        # needed for updating the possible pairs when groups change
        self.table.itemChanged.connect(self.groupChanged)
                # load values into GUI from context
        self.loadFromContext(context)

self.icase_fringe_start_edit.setRange(0, icase_max)
        self.icase_fringe_start_edit.setSingleStep(1)
        self.icase_fringe_start_edit.setValue(self._icase_fringe)
        self.icase_fringe_start_button = QPushButton("Default")

        self.icase_fringe_end_edit = QSpinBox(self)
        self.icase_fringe_end_edit.setRange(0, icase_max)
        self.icase_fringe_end_edit.setSingleStep(1)
        self.icase_fringe_end_edit.setValue(self._icase_fringe)
        self.icase_fringe_end_button = QPushButton("Default")

        self.icase_fringe_delta_edit = QSpinBox(self)
        self.icase_fringe_delta_edit.setRange(1, icase_max)
        self.icase_fringe_delta_edit.setSingleStep(1)
        self.icase_fringe_delta_edit.setValue(1)
        self.icase_fringe_delta_button = QPushButton("Default")

        self.displacement_label = QLabel("Displacement")
        self.icase_start = QLabel("iCase Start:")
        self.icase_disp_start_edit = QSpinBox(self)
        self.icase_disp_start_edit.setRange(0, icase_max)
        self.icase_disp_start_edit.setSingleStep(1)
        self.icase_disp_start_edit.setValue(self._icase_fringe)
        self.icase_disp_start_button = QPushButton("Default")

        self.icase_end_label = QLabel("iCase End:")
        self.icase_disp_end_edit = QSpinBox(self)
        self.icase_disp_end_edit.setRange(0, icase_max)
        self.icase_disp_end_edit.setSingleStep(1)
        self.icase_disp_end_edit.setValue(self._icase_fringe)
        self.icase_disp_end_button = QPushButton("Default")

def create_button(self, text, callback):
        btn = QPushButton(text)
        btn.clicked.connect(callback)
        btn.clicked.connect(lambda checked=False, opt='': self.has_been_modified(opt))
        return btn