Improvements to the code of Merkle Patricia Trie doc

[croath]

The original code sample from

ethereum-org-website/public/content/developers/docs/data-structures-and-encoding/patricia-merkle-trie/index.md

Lines 37 to 48 in e7041d3

	def update(node,path,value):
	if path == '':
	curnode = db.get(node) if node else [ NULL ] * 17
	newnode = curnode.copy()
	newnode[-1] = value
	else:
	curnode = db.get(node) if node else [ NULL ] * 17
	newnode = curnode.copy()
	newindex = update(curnode[path[0]],path[1:],value)
	newnode[path[0]] = newindex
	db.put(hash(newnode),newnode)
	return hash(newnode)

is:

    def update(node,path,value):
        if path == '':
            curnode = db.get(node) if node else [ NULL ] * 17
            newnode = curnode.copy()
            newnode[-1] = value
        else:
            curnode = db.get(node) if node else [ NULL ] * 17
            newnode = curnode.copy()
            newindex = update(curnode[path[0]],path[1:],value)
            newnode[path[0]] = newindex
        db.put(hash(newnode),newnode)
        return hash(newnode)

Shall we streamline the code a little bit with reducing the repeating part, like:

    def update(node,path,value):
        curnode = db.get(node) if node else [ NULL ] * 17
        newnode = curnode.copy()
        if path == '':
            newnode[-1] = value
        else:
            newindex = update(curnode[path[0]],path[1:],value)
            newnode[path[0]] = newindex
        db.put(hash(newnode),newnode)
        return hash(newnode)

[minimalsm]

Closed by #12721