code: def is_valid_ipv4_prefix(ipv4_prefix):
      
      if not isinstance(ipv4_prefix, str):
          return False
  
      tokens = ipv4_prefix.split('/')
      if len(tokens) != 2:
          return False
  
      # Validate address/mask and return
      return is_valid_ipv4(tokens[0]) and is_valid_ip_prefix(tokens[1], 32)
docs: Returns True if *ipv4_prefix* is a valid prefix with mask.
  
      Samples:
          - valid prefix: 1.1.1.0/32, 244.244.244.1/10
          - invalid prefix: 255.2.2.2/2, 2.2.2/22, etc.