diff --git a/src/flags.rs b/src/flags.rs
new file mode 100644
index 0000000..7613aba
--- /dev/null
+++ b/src/flags.rs
@@ -0,0 +1,276 @@
+//! CLI flags module
+use super::*;
+use std::{
+    borrow::Cow,
+    any::Any,
+    error,
+    fmt,
+};
+
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum Kind<'a>
+{
+    /// Any number of these long-form arguments starting with `--`, and flag for case-sensitivity.
+    /// Can be empty to match any argument (not needing a prefix).
+    Long(&'a [&'a str], bool),
+    /// Any number of these short-form (single character) arguments together or apart (starting with `-`).
+    /// Can be empty for a single `-` character, and a flag for case-sensitivity.
+    Short(&'a [(char, )], bool),
+    /// A single `--`.
+    Terminator,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum ValueKind
+{
+    None,
+    Equals,
+    Next(usize),
+    Rest,
+}
+
+pub struct ArgState<T=()>
+{
+    user: T,
+
+    flags: Vec<(Kind<'static>, Cow<'static, str>, ValueKind, Box<(dyn FlagCallback<T, Box<dyn Any + 'static>, Box<dyn error::Error + 'static>> + 'static)>, bool, bool)>,
+}
+
+pub trait FlagCallback<U, T,E>: FnMut(&mut StateHandle<'_, U>, usize, &str) -> Result<T, E>{}
+impl<U, F, T, E> FlagCallback<U, T,E> for F
+where F: FnMut(&mut StateHandle<'_, U>, usize, &str) -> Result<T, E>,
+      T: Any + 'static,
+      E: 'static{}
+
+impl<U> ArgState<U>
+{
+    /// Push a handle to the state
+    pub fn push<T: Any + 'static,E: error::Error + 'static, F>(&mut self, kind: Kind<'static>, desc: impl Into<Cow<'static, str>>, value: ValueKind, mut handle: F, single: bool) -> usize
+    where F: FlagCallback<U, T,E> + 'static
+    {
+	let handle: Box<dyn FlagCallback<U, Box<(dyn Any + 'static)>, Box<(dyn error::Error + 'static)>>> =
+	    Box::new(move |state, index, value| handle(state, index, value)
+		     .map(|x| -> Box<(dyn Any + 'static)> {Box::new(x)})
+		     .map_err(|x| -> Box<(dyn error::Error +'static)> {Box::new(x)}));
+	self.flags.push((kind, desc.into(), value, handle, single, true));
+	self.flags.len()-1
+    }
+}
+
+#[derive(Debug, Clone)]
+enum Either<T,U>
+{
+    None,
+    One(T),
+    Many(U),
+}
+
+impl<T,U> Either<T,U>
+{
+    pub fn take(&mut self) -> Self
+    {
+	std::mem::replace(self, Self::None)
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum EitherIter<T,U>
+{
+    None,
+    One(std::iter::Once<T>),
+    Many(std::iter::Fuse<U>),
+}
+
+impl<T,U> Iterator for EitherIter<T,U>
+where U: Iterator<Item=T>
+{
+    type Item = T;
+    fn next(&mut self) -> Option<Self::Item>
+    {
+	match self {
+	    Self::None => None,
+	    Self::One(one) => one.next(),
+	    Self::Many(many) => many.next(),
+	}
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+	match self {
+	    Self::None => (0, Some(0)),
+	    Self::One(_) => (1, Some(1)),
+	    Self::Many(many) => many.size_hint(),
+	}
+    }
+}
+impl<T,U: Iterator<Item=T>> std::iter::FusedIterator for EitherIter<T,U>{}
+impl<T,U: Iterator<Item=T>> std::iter::ExactSizeIterator for EitherIter<T,U>
+where U: ExactSizeIterator{}
+
+impl<T, U: IntoIterator<Item=T>> IntoIterator for Either<T, U>
+{
+    type Item= T;
+    type IntoIter = EitherIter<T, <U as IntoIterator>::IntoIter>;
+
+    fn into_iter(self) -> Self::IntoIter
+    {
+	match self {
+	    Self::None => EitherIter::None,
+	    Self::One(one) => EitherIter::One(std::iter::once(one)),
+	    Self::Many(many) => EitherIter::Many(many.into_iter().fuse())
+	}
+    }
+}
+
+
+/// A handle to mutate the arg state.
+pub struct StateHandle<'a, T>
+{
+    held: Either<String, Vec<String>>,
+    
+    state: &'a mut T,
+    args: &'a mut (dyn Iterator<Item=String> + 'a),
+
+    chk: &'a mut bool,
+
+    idx: usize,
+}
+
+impl<'a, T> StateHandle<'a,T>
+{
+    /// The user defined state
+    pub fn state(&self) -> &T
+    {
+	self.state
+    }
+    /// The mutable user defined state 
+    pub fn state_mut(&mut self) -> &mut T
+    {
+	self.state
+    }
+
+    /// The current args iterator
+    pub fn args(&self) -> &(dyn Iterator<Item=String> + 'a)
+    {
+	self.args
+    }
+    /// The mutable current args iterator
+    pub fn args_mut(&mut self) -> &mut (dyn Iterator<Item = String> + 'a)
+    {
+	self.args
+    }
+
+    /// Is this callback enabled?
+    ///
+    /// It will always start as `true`. This can be mutated to `false` to disable further checks for this argument.
+    pub fn enabled_mut(&mut self) -> &mut bool
+    {
+	self.chk
+    }
+    /// Is this callback enabled?
+    ///
+    /// This should always be `true`.
+    pub fn enabled(&mut self) -> bool
+    {
+	*self.chk
+    }
+    /// The index of the current arg
+    pub fn index(&self) -> usize
+    {
+	self.idx
+    }
+
+    /// The held values taken from the argument iterator as specified by the argument's definition.
+    ///
+    /// # Note
+    /// This moves the values, if you want to call this more than once, use `clone_held`.
+    /// If called more than once will yield no values
+    pub fn extract_held(&mut self) -> EitherIter<String, std::vec::IntoIter<String>>
+    {
+	self.held.take().into_iter()
+    }
+
+    /// Clone the held values taken from the argument iterator for this invokation.
+    ///
+    /// # Note
+    /// This clones all the values, instead of moving like `extract_held`, so multiple calls to this will yield the same clones.
+    /// However, if `extract_held` has been called, this will yield no values.
+    pub fn clone_held(&self) -> EitherIter<String, std::vec::IntoIter<String>>
+    {
+	self.held.clone().into_iter()
+    }
+}
+
+
+impl<U> ArgState<U>
+{
+    /// Parse this argument iterator.
+    ///
+    /// # Note
+    /// This mutates the argument state container indefinately, and multiple calls to it will keep the mutated state.
+    /// So this might not behave as expected (e.g. callbacks marked `single` that were fired in the first call will not be fired in the second, etc.)
+    pub fn parse<I,T: Into<String>>(&mut self, input: I) -> Result<Vec<Box<dyn Any+'static>>, Error>
+    where I: Iterator<Item=T>
+    {
+	let mut output = Vec::with_capacity(self.flags.len());
+	let mut input = input.map(Into::into).fuse();
+
+	let mut i=0;
+	while let Some(arg) = input.next()
+	{
+	    for (kind, desc, value, callback, single, chk) in self.flags.iter_mut().filter(|(_,_,_,_,_,chk)| *chk)
+	    {
+		if *single {
+		    *chk = false;
+		}
+		//TODO: Check Kind  matches `arg`, check `value` matches `input` and get the values.
+		output.push(callback(&mut StateHandle{
+		    state: &mut self.user,
+		    args: &mut input,
+		    chk,
+		    idx: i,
+		    held: Either::None, //TODO: This will be for either one `=<value>` or many `<values...>` from args as according to `value`.
+		}, i, &arg[..])
+			    .map_err(|err| Error{flag: kind.clone(), from: err, desc: Some(desc.clone().into_owned()), arg: (i, arg.clone())})?);
+	    }
+	    i+=1;
+	}
+
+	Ok(output)
+    }
+
+    /// Consume into the user-provided state value
+    #[inline] pub fn into_inner(self) -> U
+    {
+	self.user
+    }
+}
+
+#[derive(Debug)]
+pub struct Error
+{
+    flag: Kind<'static>,
+    arg: (usize, String),
+    desc: Option<String>,
+    from: Box<dyn error::Error + 'static>,
+}
+
+impl error::Error for Error
+{
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+	Some(self.from.as_ref())
+    }
+}
+
+impl fmt::Display for Error
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    {
+	writeln!(f, "Failed to parse args: {}", self.from)?;
+	writeln!(f, "\tArg {} which was {:?} failed on parsing for `{:?}`", self.arg.0, self.arg.1, self.flag)?;
+	if let Some(desc) = &self.desc {
+	    writeln!(f, "\n\tUsage of {:?}: {}", self.flag, desc)
+	} else {
+	    Ok(())
+	}
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 31f65aa..4ada776 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -34,6 +34,7 @@ mod dedup;
 mod resolve;
 mod database;
 
+mod flags;
 mod args;
 mod config;