code: def getImage(self, body, imageScalar=2, plotShape="circle", imageEncoding="base64/png", sparsity=1.0):
          
          return self._image.getImageForExpression(self._retina, body, imageScalar, plotShape, imageEncoding, sparsity)
docs: Get images for expressions
          Args:
              body, ExpressionOperation: The JSON encoded expression to be evaluated (required)
              imageScalar, int: The scale of the image (optional)
              plotShape, str: The image shape (optional)
              imageEncoding, str: The encoding of the returned image (optional)
              sparsity, float: Sparsify the resulting expression to this percentage (optional)
          Returns:
              str with the raw byte data of the image
          Raises:
              CorticalioException: if the request was not successful