ip_address_validator_map is a dictionary containing 3 initial entries: tuple containing 2 elements: list with an element, validate_ipv46_address and return value of the function _ with an argument string 'Enter a valid IPv4 or IPv6 address.' for 'both',
ip_address_validator_map = { 'both' : ( [ validate_ipv46_address ] , _ ( 'Enter a valid IPv4 or IPv6 address.' ) ) , 'ipv4' : ( [ validate_ipv4_address ] , _ ( 'Enter a valid IPv4 address.' ) ) , 'ipv6' : ( [ validate_ipv6_address ] , _ ( 'Enter a valid IPv6 address.' ) ) , }