def prefix(self, prefix_id, only_message=True):
request_url = build_url_endpoint(<EOL>'<STR_LIT:/>'.join([self.ENDPOINT, str(prefix_id)])<EOL>)<EOL>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>return<EOL><DEDENT>result = result.json()<EOL>return result['<STR_LIT:message>'] if only_message is True else result<EOL>
This method retrieve a json with the given Prefix metadata

args: Crossref Prefix (String)

return: JSON

Example:
    >>> from crossref.restful import Prefixes
    >>> prefixes = Prefixes()
    >>> prefixes.prefix('10.1590')
    {'name': 'FapUNIFESP (SciELO)', 'member': 'http://id.crossref.org/member/530',
    'prefix': 'http://id.crossref.org/prefix/10.1590'}