text: """
  The acssum module contains a function `acssum` that calls the ACSSUM executable.
  Use this function to facilitate batch runs of ACSSUM.
  
  Examples
  --------
  
  >>> from acstools import acssum
  >>> acssum.acssum('*flt.fits', 'combined_image.fits')
  
  For help usage use ``exe_args=['--help']``
  
  """
  # STDLIB
  import os
  import subprocess  # nosec
  
  __taskname__ = "acssum"
  __version__ = "1.0"
  __vdate__ = "18-Dec-2012"
  __all__ = ['acssum']
  
  
  def acssum(input, output, exec_path='', time_stamps=False, verbose=False,
             quiet=False, exe_args=None):
      r"""
      Run the acssum.e executable as from the shell.
  
      Parameters
      ----------
      input : str or list of str
          Input filenames in one of these formats:
  
              * a Python list of filenames
              * a partial filename with wildcards ('\*flt.fits')
              * filename of an ASN table ('j12345670_asn.fits')
              * an at-file (``@input``)
  
      output : str
          Output filename.
          If `output` is '' and `input` is '\*_asn.fits',
          `output` will be automatically set to '\*_sfl.fits'.
          Otherwise, it is an error not to provide a specific `output`.
  
      exec_path : str, optional
          The complete path to ACSSUM executable.
          If not given, run ACSSUM given by 'acssum.e'.
  
      time_stamps : bool, optional
          Set to True to turn on the printing of time stamps.
  
      verbose : bool, optional
          Set to True for verbose output.
  
      quiet : bool, optional
          Set to True for quiet output.
  
      exe_args : list, optional
          Arbitrary arguments passed to underlying executable call.
          Note: Implementation uses subprocess.call and whitespace is not
          permitted. E.g. use exe_args=['--nThreads', '1']
  
      """
      from stsci.tools import parseinput  # Optional package dependency
  
      if exec_path:
          if not os.path.exists(exec_path):
              raise OSError('Executable not found: ' + exec_path)
          call_list = [exec_path]
      else:
          call_list = ['acssum.e']
  
      # Parse input to get list of filenames to process.
      # acssum.e only takes 'file1,file2,...'
      infiles, dummy_out = parseinput.parseinput(input)
      call_list.append(','.join(infiles))
  
      call_list.append(output)
  
      if time_stamps:
          call_list.append('-t')
  
      if verbose:
          call_list.append('-v')
  
      if quiet:
          call_list.append('-q')
  
      if exe_args:
          call_list.extend(exe_args)
  
      subprocess.check_call(call_list)  # nosec
  