Write a script to parse a web server log and count the number of unique IP addresses.
Implement count_unique_ips(log_lines), where log_lines is a list of strings. Each non-empty line begins with an IP address followed by whitespace-separated web server log fields. Return the number of distinct IP addresses. Ignore empty lines; inputs contain valid IPv4 or IPv6 addresses.
def count_unique_ips(log_lines):