code: def _validate(opts):
      
      if all([vi.validate(opts),
              ve.validate(opts),
              vw.validate(opts),
              vo.validate(opts)]):
          return True
      else:
          raise ValidationException("Arguments did not pass validation. Check "
                                    "your inputs.")
docs: Perform validation operations on opts, a namespace created from
      command-line arguments. Returns True if all validation tests are successful.
  
      Runs validation() methods in validate_input.py, validate_extensions.py,
      validate_overwrite.py, and validate_wrapper.py
  
      Required attributes on opts:
      * input: String giving the path to input files
      * output: String giving the path to output destination
      * wrapper: String specifying the wrapper format
      * extensions: List of strings specifying the file extensions to look for
      * overwrite: Boolean specifying whether the original input files should
                   be overridden
  
      :param opts: namespace containing necessary parameters
      :raises ValidationException: if one or more of the tests are unsuccessful
      :raises ValueError: if opts is not a namespace with the correct parameters
      :return: True, if all tests are successful