code: def add_index_to_pipfile(self, index, verify_ssl=True):
          
          # Read and append Pipfile.
          p = self.parsed_pipfile
          try:
              self.get_source(url=index)
          except SourceNotFound:
              source = {"url": index, "verify_ssl": verify_ssl}
          else:
              return
          source["name"] = self.src_name_from_url(index)
          # Add the package to the group.
          if "source" not in p:
              p["source"] = [source]
          else:
              p["source"].append(source)
          # Write Pipfile.
          self.write_toml(p)
docs: Adds a given index to the Pipfile.