code: def _convert_extras_requirements(self):
          
          spec_ext_reqs = getattr(self, 'extras_require', None) or {}
          self._tmp_extras_require = defaultdict(list)
          for section, v in spec_ext_reqs.items():
              # Do not strip empty sections.
              self._tmp_extras_require[section]
              for r in pkg_resources.parse_requirements(v):
                  suffix = self._suffix_for(r)
                  self._tmp_extras_require[section + suffix].append(r)
docs: Convert requirements in `extras_require` of the form
          `"extra": ["barbazquux; {marker}"]` to
          `"extra:{marker}": ["barbazquux"]`.