<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def post_merge_request(profile, payload):
 """Do a POST request to Github's API to merge. Args: profile A profile generated from ``simplygithub.authentication.profile``. Such profiles tell this module (i) the ``repo`` to connect to, and (ii) the ``token`` to connect with. payload A dict of information to pass to Github's API as the payload for a merge request, something like this:: { "base": <base>, "head": <head>, "commit_message": <mesg>} Returns: The response returned by the ``requests`` library when it does the POST request. """

    repo = profile["repo"]
    url = GITHUB_API_BASE_URL + "repos/" + repo + "/merges"
    headers = get_headers(profile)
    response = requests.post(url, json=payload, headers=headers)
    return response