old_contents: from collections import namedtuple
  
  Network = namedtuple('Network', [
      'network_name',
      'network_shortname',
      'pubkeyhash',
      'wif_prefix',
      'scripthash',
      'magicbytes',
      'msgPrefix',
      'tx_timestamp',
      'denomination',
  ])
  
  
  '''
  Network name should be capitalized, for testnet append "-testnet".
  For abbreviation prefix testnet of the network with "t".
  '''
  
  networks = (
      # Peercoin mainnet
      Network("Peercoin", "ppc", b'37', b'b7', b'75', b'e6e8e9e5', b'\x17PPCoin Signed Message:\n', True, 1000000),
      # Peercoin testnet
      Network("Peercoin-testnet", "tppc", b'6f', b'ef', b'c4', b'cbf2c0ef', b'\x17PPCoin Signed Message:\n', True, 1000000),
      # Bitcoin mainnet
      Network("Bitcoin", "btc", b'00', b'80', b'05', b'd9b4bef9', b'\x18Bitcoin Signed Message:\n' ,False, 100000000),
      # Bitcoin testnet
      Network("Bitcoin-testnet", "tbtc", b'6f', b'ef', b'c4', b'dab5bffa', b'\x18Bitcoin Signed Message:\n', False, 100000000)
  )
  
  def query(query):
      '''find matching parameter among the networks'''
  
      for network in networks:
          for field in network:
              if field == query:
                  return network
  
new_contents: from collections import namedtuple
  
  Network = namedtuple('Network', [
      'network_name',
      'network_shortname',
      'pubkeyhash',
      'wif_prefix',
      'scripthash',
      'magicbytes',
      'msgPrefix',
      'min_tx_fee',
      'tx_timestamp',
      'denomination',
  ])
  
  
  '''
  Network name should be capitalized, for testnet append "-testnet".
  For abbreviation prefix testnet of the network with "t".
  '''
  
  networks = (
      # Peercoin mainnet
      Network("Peercoin", "ppc", b'37', b'b7', b'75', b'e6e8e9e5',
              b'\x17PPCoin Signed Message:\n', float(0.01), True, 1000000),
      # Peercoin testnet
      Network("Peercoin-testnet", "tppc", b'6f', b'ef', b'c4', b'cbf2c0ef',
              b'\x17PPCoin Signed Message:\n', float(0.01), True, 1000000),
      # Bitcoin mainnet
      Network("Bitcoin", "btc", b'00', b'80', b'05', b'd9b4bef9',
              b'\x18Bitcoin Signed Message:\n', 0, False, 100000000),
      # Bitcoin testnet
      Network("Bitcoin-testnet", "tbtc", b'6f', b'ef', b'c4', b'dab5bffa',
              b'\x18Bitcoin Signed Message:\n', 0, False, 100000000)
  )
  
  def query(query):
      '''find matching parameter among the networks'''
  
      for network in networks:
          for field in network:
              if field == query:
                  return network
  
subject: add min_tx_fee network parameter.