Function set_from_env 

pub fn set_from_env(var: &str) -> Option<BTreeSet<String>>

Return Option<BTreeSet> if the environment variable is present and non-empty.

Example

use agentic_tools_utils::cli::set_from_env;

// Returns None when var is not set
let value = set_from_env("NONEXISTENT_VAR_12345");
assert!(value.is_none());