Adds some minor comments

crates/day_7/src/day_7.rs

@@ -45,6 +45,8 @@ impl Day7
 
 	fn solve_first_case(self: &mut Self) -> String
 	{
+		// The engineers just need the total calibration result, 
+		// which is the sum of the test values from just the equations that could possibly be true.
 		
 		self.final_result.to_string()
 	}

crates/day_7/src/equation.rs

@@ -58,4 +58,13 @@ impl Equation
 
 		println!();
 	}
+
+	// Returns None if the equation can not be made true
+	// NOTE: Operators are always evaluated left-to-right, not according to precedence rules!
+	pub fn can_be_true(self: &Equation) -> Option<Vec<Operators>>
+	{
+		
+
+		None
+	}
 }