from caffe2.python import workspace, model_helper, brew                                                                 
import numpy as np                                                                                                      
import inspect                                                       
                                                                                                                                                                                                                            x = np.ones((4, 100, 100, 3)).astype(np.float32)  
workspace.FeedBlob('x', x)                                                                                              
m = model_helper.ModelHelper(name='train')                                                                              
print(dir(m))                                                                                                           
conv1 = brew.conv(m, 'x', 'conv_1', 3, 5, 3)                                                                            
workspace.RunNetOnce(m.param_init_net)                                                                                  
workspace.CreateNet(m.net, overwrite=True)                                                                              
print(dir(workspace))                                                                                                   
for i in range(0, 2):                                                                                                   
    workspace.RunNet(m.net)

why this is throwing error ?