// Add a string with zero slashes: resulting URL gains one slash.
    assertThat(base.newBuilder().addPathSegments("").build().encodedPath)
      .isEqualTo("/a/b/c/")
    assertThat(base.newBuilder().addPathSegments("d").build().encodedPath)
      .isEqualTo("/a/b/c/d")

    // Add a string with one slash: resulting URL gains two slashes.

    * This allows having a router for `/cats` and all its *path operations*, while having one of them for `/cats`.
    * Now it doesn't have to be only `/cats/` (with a trailing slash).
    * To use it, declare the path in the *path operation* as the empty string (`""`).
    * PR [#415](https://github.com/tiangolo/fastapi/pull/415) by [@vitalik](https://github.com/vitalik).

023E          ; mapped                 ; 2C66          # 4.1  LATIN CAPITAL LETTER T WITH DIAGONAL STROKE
023F..0240    ; valid                                  # 4.1  LATIN SMALL LETTER S WITH SWASH TAIL..LATIN SMALL LETTER Z WITH SWASH TAIL
0241          ; mapped                 ; 0242          # 4.1  LATIN CAPITAL LETTER GLOTTAL STOP
0242          ; valid                                  # 5.0  LATIN SMALL LETTER GLOTTAL STOP