code: def get_aspect(self, xspan, yspan):
          
          if self.data_aspect:
              return (yspan/xspan)*self.data_aspect
          elif self.aspect == 'equal':
              return xspan/yspan
          elif self.aspect == 'square':
              return 1
          elif self.aspect is not None:
              return self.aspect
          elif self.width is not None and self.height is not None:
              return self.width/self.height
          else:
              return 1
docs: Computes the aspect ratio of the plot