docs: def get_agent_requirement_line(check, version):
      """
      Compose a text line to be used in a requirements.txt file to install a check
      pinned to a specific version.
      """
      package_name = get_package_name(check)
  
      # no manifest
      if check in ('datadog_checks_base', 'datadog_checks_downloader'):
          return '{}=={}'.format(package_name, version)
  
      m = load_manifest(check)
      platforms = sorted(m.get('supported_os', []))
  
      # all platforms
      if platforms == ALL_PLATFORMS:
          return '{}=={}'.format(package_name, version)
      # one specific platform
      elif len(platforms) == 1:
          return "{}=={}; sys_platform == '{}'".format(package_name, version, PLATFORMS_TO_PY.get(platforms[0]))
      elif platforms:
          if 'windows' not in platforms:
              return "{}=={}; sys_platform != 'win32'".format(package_name, version)
          elif 'mac_os' not in platforms:
              return "{}=={}; sys_platform != 'darwin'".format(package_name, version)
          elif 'linux' not in platforms:
              return "{}=={}; sys_platform != 'linux2'".format(package_name, version)
  
      raise ManifestError("Can't parse the `supported_os` list for the check {}: {}".format(check, platforms))