code: def within_bounding_box(self, limits):
          
          is_valid = np.logical_and(
              self.catalogue.data['longitude'] >= limits[0],
              np.logical_and(self.catalogue.data['longitude'] <= limits[2],
                             np.logical_and(
                                 self.catalogue.data['latitude'] >= limits[1],
                                 self.catalogue.data['latitude'] <= limits[3])))
          return self.select_catalogue(is_valid)
docs: Selects the earthquakes within a bounding box.
  
          :parameter limits:
              A list or a numpy array with four elements in the following order:
                  - min x (longitude)
                  - min y (latitude)
                  - max x (longitude)
                  - max y (latitude)
          :returns:
              Returns a :class:htmk.seismicity.catalogue.Catalogue` instance