A python port of the router from discordjs/discord.js#1667

Router.py

# Achieved in python 3.7.x (last tested in 3.7.2)
# A script port of discord.js@master router, partly accurate as of August 19th 2019
# https://github.com/discordjs/discord.js/pull/1667
# https://github.com/discordjs/discord.js/blob/master/src/rest/APIRouter.js
"""
Issues that remain in this method of manual proxy definition:
- Calling .prop or ['prop'] subsequently adds the query to the existing state.
  Not that this is so much a problem as it is a solution, 
   but when running in a sandbox 1 mistake and the whole class trips on itself.
- Manual build method exists for compatibility purposes inside of a class context...
    without having to use enclosed private variables.
- Using .build() does not return an enclosed lambda expression or prebuilt definition
  for the purposes of passing options through to a parent manager to then handle the query.
"""

METHODS = ['get', 'post', 'delete', 'patch', 'put']

class Router:
    
    def __init__(self, *args, base: str = ""):
        self.base = base
        self.route = [self.base]

    def __call__(self, *args):
        self.route.extend(args)
        return self

    def __getattr__(self, name):
        if name.lower() in METHODS:
            return self.build()
        
        self.route.append(name)
        return self

    def __getitem__(self, key):
        if key.lower() in METHODS:
            return self.build()

        self.route.append(key)
        return self

    def build(self, separator: str = "/"):
        return separator.join(self.route)