given sublist of list python

# Python program to print all  
# sublist from a given list  
  
# function to generate all the sub lists 
def sub_lists(list1): 
  
    # store all the sublists  
    sublist = [[]] 
      
    # first loop  
    for i in range(len(list1) + 1): 
          
        # second loop  
        for j in range(i + 1, len(list1) + 1): 
              
            # slice the subarray  
            sub = list1[i:j] 
            sublist.append(sub) 
              
      
    return sublist 
  
# driver code 
l1 = [1, 2, 3] 
print(sub_lists(l1))