def post_documents(self, content_type: str, consent_id: str) -> dict:
        """Creates a document handle, calls the POST /documents endpoint.

        >>> from las import Client
        >>> client = Client(endpoint='<api endpoint>')
        >>> client.post_documents('image/jpeg', consent_id='foobar')

        :param content_type: A mime type for the document handle
        :type content_type: str
        :param consent_id: An identifier to mark the owner of the document handle
        :type consent_id: str
        :return: Document handle id and pre-signed upload url
        :rtype: dict
        :raises InvalidCredentialsException: If the credentials are invalid
        :raises TooManyRequestsException: If limit of requests per second is reached
        :raises LimitExceededException: If limit of total requests per month is reached
        :raises requests.exception.RequestException: If error was raised by requests
        """

        body = json.dumps({'contentType': content_type, 'consentId': consent_id}).encode()
        uri, headers = self._create_signing_headers('POST', '/documents', body)

        post_documents_response = requests.post(
            url=uri.geturl(),
            headers=headers,
            data=body
        )

        response = _json_decode(post_documents_response)
        return response
Creates a document handle, calls the POST /documents endpoint.

        >>> from las import Client
        >>> client = Client(endpoint='<api endpoint>')
        >>> client.post_documents('image/jpeg', consent_id='foobar')

        :param content_type: A mime type for the document handle
        :type content_type: str
        :param consent_id: An identifier to mark the owner of the document handle
        :type consent_id: str
        :return: Document handle id and pre-signed upload url
        :rtype: dict
        :raises InvalidCredentialsException: If the credentials are invalid
        :raises TooManyRequestsException: If limit of requests per second is reached
        :raises LimitExceededException: If limit of total requests per month is reached
        :raises requests.exception.RequestException: If error was raised by requests