code: def update(assembly, idict, count):
      
  
      data = iter(open(os.path.join(assembly.dirs.outfiles,
                       assembly.name+".phy"), 'r'))
  
      ntax, nchar = data.next().strip().split()
  
      ## read in max N bp at a time                                                                            
      for line in data:
          tax, seq = line.strip().split()
          idict[tax] = idict[tax][100000:]
          idict[tax] += seq[count:count+100000]
      del line
  
      return idict
docs: updates dictionary with the next .5M reads from the super long string 
      phylip file. Makes for faster reading.