title: Python: How to move index in a dict
body: <p>I am trying to move all entries in a dict from i to i+1. Also I want to double the first entry in order to modify entry 0 later.</p>
  
  <p>What I tried: </p>
  
  <pre><code>a={}
  a[0]={}
  a[1]={}
  a[0][1]='a_0_1'
  a[1][1]='a_1_1'
  b = a.copy()
  c = {}
  for i in range(0, len(b)):     
    c[i+1]=b[i]
  c[0]=b[0]   
  c[0][1] = 'c_0_1'
  </code></pre>
  
  <p>I get results that I completely fail to understand. The entries are changed in all dicts. Why is that happening?</p>