Raise ValueError when user selects incopatable formats #190
Description
This code fails because RDF is not a valid response format for a SELECT query:
from SPARQLWrapper import SPARQLWrapper, RDF, JSON, XML
sparql = SPARQLWrapper('http://ja.dbpedia.org/sparql')
sparql.setQuery('select * where { ?x ?y ?z. } limit 1')
sparql.setReturnFormat(RDF)
results = sparql.query().convert()The code should not fail but should raise a ValueError Exception and explain why.