code: def _error_string(error, k=None):
      
      package = error.getPackage()
      if package == '':
          package = 'core'
  
      template = 'E{} ({}): {} ({}, L{}); {}; {}'
      error_str = template.format(k, error.getSeverityAsString(),
                                  error.getCategoryAsString(), package,
                                  error.getLine(), error.getShortMessage(),
                                  error.getMessage())
      return error_str
docs: String representation of SBMLError.
  
      Parameters
      ----------
      error : libsbml.SBMLError
      k : index of error
  
      Returns
      -------
      string representation of error