docs: def combinePlinkBinaryFiles(prefixes, outPrefix):
      """Combine Plink binary files.
  
      :param prefixes: a list of the prefix of the files that need to be
                       combined.
      :param outPrefix: the prefix of the output file (the combined file).
  
      :type prefixes: list
      :type outPrefix: str
  
      It uses Plink to merge a list of binary files (which is a list of prefixes
      (strings)), and create the final data set which as ``outPrefix`` as the
      prefix.
  
      """
      # The first file is the bfile, the others are the ones to merge
      outputFile = None
      try:
          outputFile = open(outPrefix + ".files_to_merge", "w")
      except IOError:
          msg = "%(outPrefix)s.filesToMerge: can't write file" % locals()
          raise ProgramError(msg)
  
      for prefix in prefixes[1:]:
          print >>outputFile, " ".join([
              prefix + i for i in [".bed", ".bim", ".fam"]
          ])
  
      # Closing the output files
      outputFile.close()
  
      # Runing plink
      plinkCommand = ["plink", "--noweb", "--bfile", prefixes[0],
                      "--merge-list", outPrefix + ".files_to_merge",
                      "--make-bed", "--out", outPrefix]
      runCommand(plinkCommand)