clicked.connect() does not wait for click and makes widget disappear

Question

For some reason the clicked.connect() method does not wait for click and also makes my widget disappear.

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_Form():
    def __init__(self, nCode_analysis_set_up):
        nCode_analysis_set_up.resize(300, 60)
        nCode_analysis_set_up.setWindowFlags(nCode_analysis_set_up.windowFlags() | QtCore.Qt.MSWindowsFixedSizeDialogHint)
        nCode_analysis_set_up.setWindowTitle("nCode analysis set-up")
        self.importButton = QtWidgets.QPushButton(nCode_analysis_set_up)
        self.importButton.setGeometry(QtCore.QRect(10, 10, 280, 40))
        self.importButton.setText("Open import model")
        self.importButton.clicked.connect(self.input_model(nCode_analysis_set_up))

    def input_model(self,nCode_analysis_set_up):
        fileName, _ = QtWidgets.QFileDialog.getOpenFileName(None, "Select model","","Input deck (*.inp)",".inp")
        fileName = str(fileName)

        if fileName:
            nCode_analysis_set_up.resize(500, 150)
            self.importButton.deleteLater()

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    nCode_analysis_set_up = QtWidgets.QWidget()
    ui = Ui_Form(nCode_analysis_set_up)
    nCode_analysis_set_up.show()
    sys.exit(app.exec_())

If I comment out the click.connect method it works well and my single button form shows up. Can anyone see what I'm doing wrong?