code: def calculate_windows(self, **kwargs):
          
          windows = find_windows(self.elements, self.coordinates, **kwargs)
          if windows:
              self.properties.update(
                  {
                      'windows': {
                          'diameters': windows[0], 'centre_of_mass': windows[1],
                      }
                  }
              )
              return windows[0]
          else:
              self.properties.update(
                  {'windows': {'diameters': None,  'centre_of_mass': None, }}
              )
          return None
docs: Return the diameters of all windows in a molecule.
  
          This function first finds and then measures the diameters of all the
          window in the molecule.
  
          Returns
          -------
          :class:`numpy.array`
              An array of windows' diameters.
  
          :class:`NoneType`
              If no windows were found.