batch size greater than 1

[amruz]

when i try to use batch size greater than 1 i am getting error as follows

image_a = np.stack(data_A[iter*self._batch_size:(iter+1)*self._batch_size]) File "/volume/software/common/foreign_packages/NumPy/1.14.5/osl42-x86_64/lib/python2.7/site-packages/numpy/core/shape_base.py", line 349, in stack raise ValueError('need at least one array to stack') ValueError: need at least one array to stack

can anyone please help me with this?