Code structure for fixed width area.

src/parser/fixed_width_area.rs

@@ -0,0 +1,11 @@
+use super::Context;
+use crate::error::Res;
+use crate::parser::FixedWidthArea;
+
+#[tracing::instrument(ret, level = "debug")]
+pub fn fixed_width_area<'r, 's>(
+    context: Context<'r, 's>,
+    input: &'s str,
+) -> Res<&'s str, FixedWidthArea<'s>> {
+    todo!()
+}