new_contents: #! /usr/bin/env python
  
  
  class PymtError(Exception):
  
      pass
  
  
  class BmiError(PymtError):
      def __init__(self, fname, status):
          self._fname = fname
          self._status = status
  
      def __str__(self):
          return "Error calling BMI function: {fname} ({code})".format(
              fname=self._fname, code=self._status
          )
  
subject: Add pymt.errors module.