def all(self):
request_url = build_url_endpoint(self.ENDPOINT, self.context)<EOL>request_params = dict(self.request_params)<EOL>result = self.do_http_request(<EOL>'<STR_LIT>',<EOL>request_url,<EOL>data=request_params,<EOL>custom_header=str(self.etiquette)<EOL>)<EOL>if result.status_code == <NUM_LIT>:<EOL><INDENT>raise StopIteration()<EOL><DEDENT>result = result.json()<EOL>for item in result['<STR_LIT:message>']['<STR_LIT>']:<EOL><INDENT>yield item<EOL><DEDENT>
This method retrieve an iterator with all the available types.

return: iterator of crossref document types

Example:
    >>> from crossref.restful import Types
    >>> types = Types()
    >>> [i for i in types.all()]
    [{'label': 'Book Section', 'id': 'book-section'},
    {'label': 'Monograph', 'id': 'monograph'},
    {'label': 'Report', 'id': 'report'},
    {'label': 'Book Track', 'id': 'book-track'},
    {'label': 'Journal Article', 'id': 'journal-article'},
    {'label': 'Part', 'id': 'book-part'},
    ...
    }]