code: def install_tools(dependencies):
      
      tools = getattr(easy.options, "tools", {})
      for dependency in iterutil.flatten(dependencies):
          dependency = tools.get(dependency, dependency)
          try:
              pkg_resources.require(dependency)
          except pkg_resources.DistributionNotFound:
              vsh("pip", "install", "-q", dependency)
              dependency = pkg_resources.require(dependency)
              easy.info("Installed required tool %s" % (dependency,))
docs: Install a required tool before using it, if it's missing.
  
          Note that C{dependencies} can be a distutils requirement,
          or a simple name from the C{tools} task configuration, or
          a (nested) list of such requirements.