def get_institution_url(base_url):
base_url = base_url.rstrip('<STR_LIT:/>')<EOL>index = base_url.find('<STR_LIT>')<EOL>if index != -<NUM_LIT:1>:<EOL><INDENT>return base_url[<NUM_LIT:0>:index]<EOL><DEDENT>return base_url<EOL>
Clean up a given base URL.

:param base_url: The base URL of the API.
:type base_url: str
:rtype: str