docs: def install_requirements(self, requirements, **kw):
          """
          Manually install a requirement set from binary and/or wheel distributions.
  
          :param requirements: A list of :class:`pip_accel.req.Requirement` objects.
          :param kw: Any keyword arguments are passed on to
                     :func:`~pip_accel.bdist.BinaryDistributionManager.install_binary_dist()`.
          :returns: The number of packages that were just installed (an integer).
          """
          install_timer = Timer()
          install_types = []
          if any(not req.is_wheel for req in requirements):
              install_types.append('binary')
          if any(req.is_wheel for req in requirements):
              install_types.append('wheel')
          logger.info("Installing from %s distributions ..", concatenate(install_types))
          # Track installed files by default (unless the caller specifically opted out).
          kw.setdefault('track_installed_files', True)
          num_installed = 0
          for requirement in requirements:
              # When installing setuptools we need to uninstall distribute,
              # otherwise distribute will shadow setuptools and all sorts of
              # strange issues can occur (e.g. upgrading to the latest
              # setuptools to gain wheel support and then having everything
              # blow up because distribute doesn't know about wheels).
              if requirement.name == 'setuptools' and is_installed('distribute'):
                  uninstall('distribute')
              if requirement.is_editable:
                  logger.debug("Installing %s in editable form using pip.", requirement)
                  with TransactionalUpdate(requirement):
                      command = InstallCommand()
                      opts, args = command.parse_args(['--no-deps', '--editable', requirement.source_directory])
                      command.run(opts, args)
              elif requirement.is_wheel:
                  logger.info("Installing %s wheel distribution using pip ..", requirement)
                  with TransactionalUpdate(requirement):
                      wheel_version = pip_wheel_module.wheel_version(requirement.source_directory)
                      pip_wheel_module.check_compatibility(wheel_version, requirement.name)
                      requirement.pip_requirement.move_wheel_files(requirement.source_directory)
              else:
                  logger.info("Installing %s binary distribution using pip-accel ..", requirement)
                  with TransactionalUpdate(requirement):
                      binary_distribution = self.bdists.get_binary_dist(requirement)
                      self.bdists.install_binary_dist(binary_distribution, **kw)
              num_installed += 1
          logger.info("Finished installing %s in %s.",
                      pluralize(num_installed, "requirement"),
                      install_timer)
          return num_installed