Initializing and setting elements:
---zero---
---one---
---two---
---three---
---four---

strvector size after first removing one element, and then the rest:
0

Resize to three elements, and set them:
---zero---
---one---
---two---

Then copy the first element over the third element:
---zero---
---one---
---zero---

Make a copy of the strvector and set the last element of the copy:
---zero---
---one---
---copy two---

Append the copy to the strvector:
---zero---
---one---
---zero---
---zero---
---one---
---copy two---

Add two strings at the end:
---zero---
---one---
---zero---
---zero---
---one---
---copy two---
---zeroth---
---first---

strvector size after clearing it:
0
