Checks to see if an IP address is used for local communications within
    a private network as specified by RFC 1918

def is_rfc1918(ip):
    """Checks to see if an IP address is used for local communications within
    a private network as specified by RFC 1918
    """
    if ip_between(ip, "10.0.0.0", "10.255.255.255"):
        return True
    elif ip_between(ip, "172.16.0.0", "172.31.255.255"):
        return True
    elif ip_between(ip, "192.168.0.0", "192.168.255.255"):
        return True
    else:
        return False