def check_requirements(self, reqs):<EOL>
missing = set()<EOL>conflicting = set()<EOL>if reqs:<EOL><INDENT>ws = WorkingSet(self._lib_dirs)<EOL>for req in reqs:<EOL><INDENT>try:<EOL><INDENT>if ws.find(Requirement.parse(req)) is None:<EOL><INDENT>missing.add(req)<EOL><DEDENT><DEDENT>except VersionConflict as e:<EOL><INDENT>conflicting.add((str(e.args[<NUM_LIT:0>].as_requirement()),<EOL>str(e.args[<NUM_LIT:1>])))<EOL><DEDENT><DEDENT><DEDENT>return conflicting, missing<EOL>
Return 2 sets:
            - conflicting requirements: set of (installed, wanted) reqs tuples
            - missing requirements: set of reqs