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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _update_or_init_po_files(target, source, env):
 """ Action function for `POUpdate` builder """

  import SCons.Action
  from SCons.Tool.GettextCommon import _init_po_files
  for tgt in target:
    if tgt.rexists():
      action = SCons.Action.Action('$MSGMERGECOM', '$MSGMERGECOMSTR')
    else:
      action = _init_po_files
    status = action([tgt], source, env)
    if status : return status
  return 0