Break apart is_boolean test into true/false variants

src/lexer/char.rs

@@ -11,7 +11,8 @@ pub trait Lexable {
     fn is_identifier_subsequent(&self) -> bool;
     fn is_identifier_single(&self) -> bool;
     fn is_hash(&self) -> bool;
-    fn is_boolean(&self) -> bool;
+    fn is_boolean_true(&self) -> bool;
+    fn is_boolean_false(&self) -> bool;
     fn is_newline(&self) -> bool;
 }
 
@@ -40,8 +41,12 @@ impl Lexable for char {
         *self == '#'
     }
 
-    fn is_boolean(&self) -> bool {
-        *self == 't' || *self == 'f'
+    fn is_boolean_true(&self) -> bool {
+        *self == 't'
+    }
+
+    fn is_boolean_false(&self) -> bool {
+        *self == 'f'
     }
 
     fn is_newline(&self) -> bool {