def invoke_function(self, function_name, **function_params):
url = self.build_url(self._endpoints.get('<STR_LIT>').format(function_name))<EOL>response = self.session.post(url, data=function_params)<EOL>if not response:<EOL><INDENT>return None<EOL><DEDENT>data = response.json()<EOL>error = data.get('<STR_LIT:error>')<EOL>if error is None:<EOL><INDENT>return data.get('<STR_LIT:value>')<EOL><DEDENT>else:<EOL><INDENT>raise FunctionException(error)<EOL><DEDENT>
Invokes an Excel Function