code: def filter(self, value, model=None, context=None):
          
  
          value = str(value)
          pattern = r'\d+'
          found = ''.join(re.findall(pattern, value))
  
          if found and self.to_int:
              found = int(found)
  
          return found
docs: Filter
          Performs value filtering and returns filtered result.
  
          :param value:           input value
          :param model:           parent model being validated
          :param context:         object, filtering context
          :return:                filtered value