How to remove a meaning from a dictionary during a cycle for

I somehow suddenly ran into such a problem. During the & nbsp; for I need to remove the records from it, but how can I tu out the error:

  Runtimeroror: Dictionary CHANGED SIZE DURING ITERANN  

I even tried to make a dictionary’s snapshot before iteration and Irte the double is removing from the original.

   & gt; & gt; & gt;  OT = { 12 :  'wqe' ,  13 :  'wqe' ,  14 :  'wqe' ,  15 :  '' '' '' ''}}   & gt; & gt;  OT1 = OT  & gt; & gt; & gt;   for  i  in  ot1:   ...   del  ot  ...  traceback (Most Recent Call Last):  File , Line  1 ,  in  & lt; module & gt; runtimeerror: dictionary Changed size duing iteration    
 how to delete correctly? A little wrongly so correctly: 
  
   & gt; & gt; & gt;  OT = { 12 :  'wqe' ,  13 :  'wqe' ,  14 :  'wqe' ,  15 :  '' '' '' ''}}   & gt; & gt;  OT1 = OT.copy ()   & gt; & gt; & gt;   for  i  in  ot1:   ...   del  ot