Improve documentation of net system module

docs/reference/model/net.md

@@ -8,35 +8,45 @@ weight: 100
 
 ## split_host_port
 
-`split_host_port(ip_end_point: str) -> List[str]`
+`split_host_port(ip_end_point: str) -> [str]`
 
-Split the `host` and `port` from the `ip_end_point`.
+Splits an `ip_end_point` of the form `host:port` or `[host]:port` into a `host` and `port`.
+Returns a list containing the `host` and `port`, respectively.
+
+An IPv6 literal in the `ip_end_point` must be enclosed in square brackets and will be returned
+without the enclosing brackets.
 
 ```python
 import net
 
-host_and_port = net.split_host_port("B-K0NZJGH6-0048.local:80")
-host_port = net.join_host_port("B-K0NZJGH6-0048.local", 80)
+assert net.split_host_port("B-K0NZJGH6-0048.local:80") == ["B-K0NZJGH6-0048.local", "80"]
+assert net.split_host_port("[::1]:80") == ["::1", "80"]
 ```
 
 ## join_host_port
 
-`join_host_port(host, port) -> str`
+`join_host_port(host: str, port: int | str) -> str`
 
-Merge the `host` and `port`.
+Combines `host` and `port` into a network address of the form `host:port`.
+If `host` contains a colon, as found in an IPv6 address literal, then returns `[host]:port`. 
 
 ```python
 import net
 
-host_and_port = net.split_host_port("B-K0NZJGH6-0048.local:80")
-host_port = net.join_host_port("B-K0NZJGH6-0048.local", 80)
+assert net.join_host_port("B-K0NZJGH6-0048.local", 80) == "B-K0NZJGH6-0048.local:80"
+assert net.join_host_port("::1", "80") == "[::1]:80"
 ```
 
 ## fqdn
 
 `fqdn(name: str = '') -> str`
 
-Return Fully Qualified Domain Name (FQDN).
+Returns the Fully Qualified Domain Name (FQDN) of `name`, determined by
+performing a reverse DNS lookup on the first address returned by a forward DNS
+lookup. If `name` is specified as or defaults to the empty string, uses the system
+hostname for the forward DNS lookup.
+
+This function is not supported on the WASM target.
 
 ```python
 import net
@@ -46,21 +56,24 @@ fqdn = net.fqdn()
 
 ## parse_IP
 
-`parse_IP(ip) -> str`
+`parse_IP(ip: str) -> str`
 
-Parse `ip` to a real IP address
+Parses the IP address `ip` and returns it in canonical form. If `ip` does
+not have valid syntax, returns the empty string.
 
 ```python
 import net
 
-ip = net.parse_IP("192.168.0.1")
+assert net.parse_IP("192.168.0.1") == "192.168.0.1"
+assert net.parse_IP("2001:0db8:0:0:0:0:0:0") == "2001:db8::"
+assert net.parse_IP("invalid") == ""
 ```
 
 ## to_IP4
 
-`to_IP4(ip) -> str`
+`to_IP4(ip: str) -> str`
 
-Get the IP4 form of `ip`.
+A synonym for `parse_IP()`.
 
 ```python
 import net
@@ -72,7 +85,7 @@ ip = net.to_IP4("192.168.0.1")
 
 `to_IP16(ip) -> int`
 
-Get the IP16 form of `ip`.
+A synonym for `parse_IP()`.
 
 ```python
 import net
@@ -82,9 +95,9 @@ ip = net.to_IP16("192.168.0.1")
 
 ## IP_string
 
-`IP_string(ip: str | int) -> str`
+`IP_string(ip: str) -> str`
 
-Get the IP string.
+A synonym for `parse_IP()`.
 
 ```python
 import net
@@ -96,48 +109,61 @@ ip = net.IP_string("192.168.0.1")
 
 `is_IPv4(ip: str) -> bool`
 
-Whether `ip` is a IPv4 one.
+If `ip` is a valid IPv4 address, returns `True`. Otherwise, returns `False`.
 
 ```python
 import net
 
-ip = net.is_IPv4("192.168.0.1")
+assert net.is_IPv4("192.168.0.1") == True
+assert net.is_IPv4("::1") == False
+assert net.is_IPv4("invalid") == False
 ```
 
 ## is_IP
 
 `is_IP(ip: str) -> bool`
 
-Whether `ip` is a valid ip address.
+If `ip` is a valid IPv4 or IPv6 address, returns `True`. Otherwise, returns `False`.
 
 ```python
 import net
 
-ip = net.is_IP("192.168.0.1")
+assert net.is_IPv4("192.168.0.1") == True
+assert net.is_IPv4("::1") == True
+assert net.is_IPv4("invalid") == False
 ```
 
 ## is_loopback_IP
 
 `is_loopback_IP(ip: str) -> bool`
 
-Whether `ip` is a loopback one.
+If `ip` is an IPv4 or IPv6 loopback address, returns `True`. Otherwise, returns `False`.
 
 ```python
 import net
 
-isip = net.is_loopback_IP("127.0.0.1")
+assert net.is_loopback_IP("127.0.0.1") == True
+assert net.is_loopback_IP("127.1.2.3") == True
+assert net.is_loopback_IP("192.168.0.1") == False
+assert net.is_loopback_IP("::1") == True
+assert net.is_loopback_IP("::") == False
+assert net.is_loopback_IP("invalid") == False
 ```
 
 ## is_multicast_IP
 
 `is_multicast_IP(ip: str) -> bool`
 
-Whether `ip` is a multicast one.
+If `ip` is an IPv4 or IPv6 multicast address, returns `True`. Otherwise, returns `False`.
 
 ```python
 import net
 
-isip = net.is_multicast_IP("239.255.255.255")
+assert net.is_multicast_IP("239.255.255.255") == True
+assert net.is_multicast_IP("10.1.2.3") == False
+assert net.is_multicast_IP("ff02::1") == True
+assert net.is_multicast_IP("2001:0db8::") == False
+assert net.is_multicast_IP("invalid") == False
 ```
 
 ## is_interface_local_multicast_IP
@@ -192,10 +218,14 @@ isip = net.is_global_unicast_IP("220.181.108.89")
 
 `is_unspecified_IP(ip: str) -> bool`
 
-Whether `ip` is a unspecified one.
+If `ip` is the IPv4 or IPv6 unspecified address, returns `True`. Otherwise, returns `False`.
 
 ```python
 import net
 
-isip = net.is_unspecified_IP("0.0.0.0")
+assert net.is_unspecified_IP("0.0.0.0") == True
+assert net.is_unspecified_IP("10.0.0.1") == False
+assert net.is_unspecified_IP("::") == True
+assert net.is_unspecified_IP("2001:0db8::") == False
+assert net.is_unspecified_IP("invalid") == False
 ```