code: def remove_study(self, first_arg, sec_arg, third_arg, fourth_arg=None, commit_msg=None):
          
          if fourth_arg is None:
              study_id, branch_name, author = first_arg, sec_arg, third_arg
              gh_user = branch_name.split('_study_')[0]
              parent_sha = self.get_master_sha()
          else:
              gh_user, study_id, parent_sha, author = first_arg, sec_arg, third_arg, fourth_arg
          if commit_msg is None:
              commit_msg = "Delete Study #%s via OpenTree API" % study_id
          return self._remove_document(gh_user, study_id, parent_sha, author, commit_msg)
docs: Remove a study
          Given a study_id, branch and optionally an
          author, remove a study on the given branch
          and attribute the commit to author.
          Returns the SHA of the commit on branch.