Especially, replace things like `type(x) == type([])` by `isinstance(list)`.

Also do `x is None` special casing.

Using the following py3 script:

import pathlib
import re
import sys

simple = {
    r"\[\]": r"list",
    r"\(\)": r"tuple",
    r"\(\d+,\)": r"tuple",
    r"\{\}": r"dict",
    r"\d+": r"int",
    r"''": r"str",
    r'""': r"str",
    r"long\(\d+\)": r"long",
}

others = {
    r"type\((.*?)\)\s*==\s*type\(\s*None\s*\)": r"\1 is None",
    r"type\((.*?)\)\s*!=\s*type\(\s*None\s*\)": r"\1 is not None",
    r"type\((.*?)\)\s*==\s*(type\(.*?\))": r"isinstance(\1, \2)",
    r"type\((.*?)\)\s*!=\s*(type\(.*?\))": r"not isinstance(\1, \2)",
}

def replace_in_all_files(root, pat, sub):
    for path in root.glob("**/*.py"):
        with path.open() as file:
            data = file.read()
        new_data = pat.sub(sub, data)
        if data != new_data:
            with path.open("w") as file:
                file.write(new_data)

root = pathlib.Path(sys.argv[1])

for str_pat, sub in simple.items():
    replace_in_all_files(
        root,
        re.compile(rf"type\((.*?)\)\s*==\s*type\(\s*{str_pat}\s*\)"),
        rf"isinstance(\1, {sub})",
    )
    replace_in_all_files(
        root,
        re.compile(rf"type\((.*?)\)\s*!=\s*type\(\s*{str_pat}\s*\)"),
        rf"not isinstance(\1, {sub})",
    )

for str_pat, sub in others.items():
    replace_in_all_files(root, re.compile(str_pat), sub)

This also helps with 2to3.