title: clustalw and muscle in Biopython
body: <p>I am having problem using biopython,I have Python version
   v3.3 and I  installed biopython-1.61.win-amd64-py3.3
  I want to align DNA sequences with <code>Clustalw</code> or <code>Muscle</code></p>
  
  <p>for <code>Clustalw:</code></p>
  
  <pre><code>from Bio.Clustalw import MultipleAlignCL
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code>No module named 'Bio.Clustalw'
  </code></pre>
  
  <p>for <code>Muscle:</code></p>
  
  <pre><code>&gt;&gt;&gt; from Bio.Align.Applications import MuscleCommandline
  &gt;&gt;&gt; muscle_cline = MuscleCommandline(input="input.fasta")
  &gt;&gt;&gt; stdout, stderr = muscle_cline()
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code>stdout, stderr = muscle_cline()
    File "..\..\lib\site-packages\Bio\Application\__init__.py", line 434, in __call__
      shell=(sys.platform!="win32"))
    File "..:\..\lib\subprocess.py", line 818, in __init__
      restore_signals, start_new_session)
    File "..:\..\lib\subprocess.py", line 1096, in _execute_child
      raise WindowsError(*e.args)
  FileNotFoundError: [WinError 2] The specified file is not found
  </code></pre>