code: def _parse_options(opts, delim):
      
      options = {}
      for opt in opts.split(delim):
          key, val = opt.split("=")
          if key.lower() == 'readpreferencetags':
              options.setdefault('readpreferencetags', []).append(val)
          else:
              # str(option) to ensure that a unicode URI results in plain 'str'
              # option names. 'normalized' is then suitable to be passed as
              # kwargs in all Python versions.
              if str(key) in options:
                  warnings.warn("Duplicate URI option %s" % (str(key),))
              options[str(key)] = unquote_plus(val)
  
      # Special case for deprecated options
      if "wtimeout" in options:
          if "wtimeoutMS" in options:
              options.pop("wtimeout")
          warnings.warn("Option wtimeout is deprecated, use 'wtimeoutMS'"
                        " instead")
  
      return options
docs: Helper method for split_options which creates the options dict.
      Also handles the creation of a list for the URI tag_sets/
      readpreferencetags portion.