feat: initial API and docs

src/utils/serde.rs

@@ -0,0 +1,16 @@
+use serde::{de, Deserialize, Deserializer};
+use std::{fmt, str::FromStr};
+
+
+pub fn empty_string_as_none<'de, D, T>(de: D) -> Result<Option<T>, D::Error>
+where
+    D: Deserializer<'de>,
+    T: FromStr,
+    T::Err: fmt::Display,
+{
+    let opt = Option::<String>::deserialize(de)?;
+    match opt.as_deref() {
+        None | Some("") => Ok(None),
+        Some(s) => FromStr::from_str(s).map_err(de::Error::custom).map(Some),
+    }
+}