`argv_array_push`::
Push a copy of a string onto the end of the array.
+`argv_array_pushl`::
+ Push a list of strings onto the end of the array. The arguments
+ should be a list of `const char *` strings, terminated by a NULL
+ argument.
+
`argv_array_pushf`::
Format a string and push it onto the end of the array. This is a
convenience wrapper combining `strbuf_addf` and `argv_array_push`.