Add pydoc-serve to show local python documentation.

With aliases pydoc2-serve pydoc3-serve.
Will try multiple possible locations, since not all distributions use
the same naming scheme.
Depends on the doc-plugin method in serve, but the user doesn’t have to
know how exactly his systems python doc folder is named.

plugins/python/python.plugin.zsh

@@ -9,6 +9,47 @@ function pyclean() {
     find ${ZSH_PYCLEAN_PLACES} -type d -name "__pycache__" -delete
 }
 
+function pydoc-serve() {
+# Serves offline python documentation
+# Args:
+#   python_doc_version: 2 or 3 (will fall back to other if necessary)
+    which serve-doc >/dev/null
+    if [ $? -ne 0 ]; then
+        echo "This function (pydoc-serve) depends on the oh-my-zsh serve plugin." >&2
+        return
+    fi
+
+    local version=$1
+
+    # python2 prints --version to stderr, python3 to stdout
+    local iv="$(python --version 2>&1 | cut -d' ' -f2 | tr '.' ' ')"
+    [ $version -ne ${iv[1]} ] \
+        && iv="$(python$version --version 2>&1 | cut -d' ' -f2 | tr '.' ' ')"
+    # Try to make this local … bash/zsh are a bad joke.
+    installed_version=(`echo $iv`)
+    local v1=${installed_version[1]}
+    local v2=${installed_version[2]}
+    local v3=${installed_version[3]}
+
+    local done=-1
+    for suffix in "" "docs"; do
+        if [ $done -ne 0 ]; then
+            serve-doc "python$v1.$v2.$v3" || \
+                serve-doc "python$v1.$v2" || \
+                serve-doc "python$v1" || \
+                serve-doc "python"
+            done=$?
+        fi
+    done
+}
+
+function pydoc2-serve() {
+    pydoc-serve 2
+}
+function pydoc3-serve() {
+    pydoc-serve 3
+}
+
 # Grep among .py files
 alias pygrep='grep --include="*.py"'