code: def src_to_dst(self, src_uri):
          
          m = re.match(self.src_uri + "/(.*)$", src_uri)
          if (m is None):
              return(None)
          rel_path = m.group(1)
          return(self.dst_path + '/' + rel_path)
docs: Return the dst filepath from the src URI.
  
          Returns None on failure, destination path on success.