/*! \page normal_page Normal to a Face This operation calculates the normal vector to the selected \b Face. \image html normaletoface.png - \b Face is the face whose Normal should be calculated. - \b Point is a point on this face. If the point is not given, the normal is calculated at the center of mass. Press \b Apply or <b>Apply and Close</b> button to publish the \b Normal \b Vector in the study. \n <b>TUI Command:</b> <em>geompy.GetNormal(Face, OptionalPoint = None)</em>. See also a \ref tui_normal_face_page "TUI example". */