from uritemplate import URITemplate, expand

# NOTE: URI params must be strings not integers

gist_uri = 'https://api.github.com/users/sigmavirus24/gists{/gist_id}'
t = URITemplate(gist_uri)
print(t.expand(gist_id='123456'))
# => https://api.github.com/users/sigmavirus24/gists/123456

# or
print(expand(gist_uri, gist_id='123456'))

# also
t.expand({'gist_id': '123456'})
print(expand(gist_uri, {'gist_id': '123456'}))

import requests

class GitHubUser(object):
    url = URITemplate('https://api.github.com/user{/login}')
    def __init__(self, name):
        self.api_url = url.expand(login=name)
        response = requests.get(self.api_url)
        if response.status_code == 200:
            self.__dict__.update(response.json())

pip install uritemplate