code: def citation_count(papers, key='ayjid', verbose=False):
      
  
      if verbose:
          print "Generating citation counts for "+unicode(len(papers))+" papers..."
  
      counts = Counter()
      for P in papers:
          if P['citations'] is not None:
              for p in P['citations']:
                  counts[p[key]] += 1
  
      return counts
docs: Generates citation counts for all of the papers cited by papers.
  
      Parameters
      ----------
      papers : list
          A list of :class:`.Paper` instances.
      key : str
          Property to use as node key. Default is 'ayjid' (recommended).
      verbose : bool
          If True, prints status messages.
  
      Returns
      -------
      counts : dict
          Citation counts for all papers cited by papers.