title: python/jython NameError
body: <p>im facing typical NameError (without any additional message) on command "cd" while importing other file.</p>
  
  <p>E.g. <strong>executor.py</strong></p>
  
  <pre><code>import sys
  from java.lang import System
  import ds_update
  
  x = ds_update.DataSource()
  x.someAction()
  </code></pre>
  
  <p>And <strong>ds_update.py</strong>
  import sys
  from java.lang import System</p>
  
  <pre><code>import sys
  from java.lang import System
  
  class DataSource:
  
    def someAction(self): 
      try:
        cd('/')
      ...
  </code></pre>
  
  <p>Got error: (if those commands are in one file, there is no problem with cd)</p>
  
  <pre><code>Problem invoking WLST - Traceback (innermost last):
    File "...\executor.py", line 17, in ?
    File "...\ds_update.py", line 11, in updateDS
  NameError: cd
  </code></pre>
  
  <p>Thank you:-)</p>