Create structure for subscript and superscript.

src/parser/subscript_and_superscript.rs

@@ -0,0 +1,20 @@
+use super::Context;
+use crate::error::Res;
+use crate::parser::util::not_yet_implemented;
+use crate::parser::Subscript;
+use crate::parser::Superscript;
+
+#[tracing::instrument(ret, level = "debug")]
+pub fn subscript<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str, Subscript<'s>> {
+    not_yet_implemented()?;
+    todo!()
+}
+
+#[tracing::instrument(ret, level = "debug")]
+pub fn superscript<'r, 's>(
+    context: Context<'r, 's>,
+    input: &'s str,
+) -> Res<&'s str, Superscript<'s>> {
+    not_yet_implemented()?;
+    todo!()
+}